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Ministry of higher education and scientific research Foundation of technical education Learning package in filed Medical physiology ( theoretical part ) Presented to the first class students Of Institute of medical technology – Baghdad Department of community health Designed by Dr. Rawaa adnan faraj 2009 -2010 1 A: Over view 1- Target population : This learning package had been designed to the first class students in the Community Health Dept. of the Institute of Medical Technology – Baghdad. 2- Rationale: This learning package will aid those who want to learn the basic physiology concepts that apply to the health field. It is also intended for students who have little or no science background. The student will discover, the concise nature of those units has made each sentence significant. Thus, the reader will be intellectually challenged to learn each new concept as it is presented. It is my hope that the students will enjoy their study of physiology and be motivated to further explore this fascinating field, especially as it relates to their occupations. 3- general target : The students are able to know and understand physiology and functions and structures of human body 2 Unit one Physiology Human physiology is the science of the mechanical, physical, and biochemical functions of humans in good health, their organs, and the cells of which they are composed. The principal level of focus of physiology is at the level of organs and systems. Most aspects of human physiology, and animal experimentation has provided much of the foundation of physiological knowledge. Anatomy and physiology are closely related fields of study: anatomy, the study of form, and physiology, the study of function,. The word physiology is form Ancient Greek: φύσις, physis, "nature, origin"; and - λογία, -logia, "study of" 1-1 The blood Blood is the life-maintaining fluid that circulates through the body's:- Heart. , arteries ,veins , capillaries The blood consists of a suspension of special cells in a liquid called plasma. In an adult man, the blood is about 1/12th of the body weight and this corresponds to 5-6 liters. Blood consists of 55 % plasma, and 45 % by cells called formed elements. The blood performs a lot of important functions. By means of the hemoglobin contained in the erythrocytes, it carries oxygen to the tissues and collects the carbon dioxide (CO2). It also conveys nutritive substances (e.g. amino acids, sugars, mineral salts) and gathers the excreted material which will be eliminated through the renal filter. The blood also carries hormones, enzymes and vitamins. It performs the defense of the organism by mean of the phagocitic activity of the leukocytes, the bactericidal power of the serum and the immune response of which the lymphocytes are the protagonists. 2-1 Functions of blood 1- Transports :(Dissolved gases (e.g. oxygen, carbon dioxide), waste products of metabolism (e.g. water, urea ), hormones ,enzymes Nutrients (such as glucose, amino acids, micro-nutrients (vitamins & minerals), fatty acids, glycerol); Plasma proteins (associated with defense, such as blood-clotting and antibodies); Blood cells (incl. white blood cells 'leucocytes', and red blood cells 'erythrocytes and platelets 2- Maintains Body Temperature. 3- Control pH ( The pH of blood must remain in the range 6.8 to 7.4, otherwise it begins to damage cells) 4- Removes toxins from the body (The kidneys filter all of the blood in the body (approx. 8 pints), 36 times every 24 hours. Toxins removed from the blood by the kidneys leave the 3 body in the urine. (Toxins also leave the body in the form of sweat.) 5- Regulation of Body Fluid Electrolytes Excess salt is removed from the body in urine, which may contain around 10g salt per day(such as in the cases of people on western diets containing more salt than the body requires 3-1 The plasma The plasma is a slightly alkaline fluid, with a typical yellowish color. It consists of 90 % water and 10% dry matter. Nine parts of it are made up by organic substances, whereas one part is made up by minerals. These organic substances are composed of (glucose), lipids (cholesterol, triglycerides, phospholipids, lecithin, fats), proteins (globulins, albumins, fibrinogen), glycoproteins, hormones (gonadothropins, erythropoietin, thrombopoietin), amino acids and vitamins. The mineral substances are dissolved in ionic form, that is dissociated into positive and negative ions. 4-1 the blood cells 1- Red blood cells (erythrocytes) The erythrocytes are the most numerous blood cells i.e. about 4-6 millions/mm3. They are also called red cells. In man and in all mammals, erythrocytes are devoid of a nucleus and have the shape of a biconcave lens. they have a nucleus. The red cells are rich in hemoglobin, a protein able to bind in a faint manner to oxygen. In the red cells of the mammalians, the lack of nucleus allows more room for hemoglobin and the biconcave shape of these cells raises the surface and cytoplasmic volume ratio. The mean life of erythrocytes is about 120 days. When they come to the end of their life, they are retained by the spleen where they are phagocyted by macrophages. 5-1 Functions of red blood cells The primary function of red blood cells, or erythrocytes, is to carry oxygen and carbon dioxide. Hemoglobin (Hgb) is an important protein in the red blood cells that carries oxygen from the lungs to all parts of our body. ----------------------------------------------------------------------------------------------------------------- Test –No. 1 Enumerate the functions of blood Test – No. 2 What is the main functions of erythrocyte 4 Unit two 1-2 White blood cells (leukocytes) Leukocytes, or white cells, are responsible for the defense of the organism. In the blood, they are much less numerous than red cells. The density of the leukocytes in the blood is 5000-7000 /mm3. Leukocytes divide in two categories: granulocytes and lymphoid cells or agranulocytes. The term granulocyte is due to the presence of granules in the cytoplasm of these cells. In the different types of granulocytes, the granules are different and help us to distinguish them. In fact, these granules have a different affinity towards neutral, acid or basic stains and give the cytoplasm different colors. So, granulocytes distinguish themselves in neutrophil, eosinophil (or acidophil) and basophil. The lymphoid cells, instead, distinguish themselves in lymphocytes and monocytes. As we will see later, even the shape of the nucleus helps us in the recognition of the leukocytes. Each type of leukocyte is present in the blood in different proportions: neutrophil 50 - 70 % eosinophil 2 - 4 % basophil 0,5 - 1 % lymphocyte 20 - 40 % monocyte 3 - 8 % 2-2 Functions of white blood cells The primary function of white blood cells, or leukocytes, is to fight infection. There are several types of white blood cells and each has its own role in fighting bacterial, viral, fungi, and parasitic infections. Types of white blood cells that are most important for helping protect the body from infection and foreign and Help heal wounds not only by fighting infection but also by ingesting matter such as dead cells, tissue debris and old red blood cells. Are our protection from foreign bodies that enter the blood stream, such as allergens. Types of white blood cells include: A granulocytes Lymphocytes. Monocytes. (granulocytes). Eosinophils. Basophils. Neutrophils 5 1- Neutrophils are very active in phagocyting bacteria and are present in large amount in the pus of wounds. Unfortunately, these cells are not able to renew the lysosomes used in digesting microbes and dead after having phagocyted a few of them. 2- Eosinophils attack parasites and phagocyte antigen-antibody complexes 3- Basophil secrete anti-coagulant and vasodilatory substances as histamines and serotonin. Even if they have a phagocytory capability, their main function is secreting substances which mediate the hypersensitivity reaction Lymphocytes :- T – lymphocyte B – lymphocyte are cells which, besides being present in the blood, populate the lymphoid tissues and organs too, as well as the lymph circulating in the lymphatic vessel. The lymphoid organs include thymus, bone marrow ,spleen, lymphoid nodules, palatine tonsils, Peyer's patches and lymphoid tissue of respiratory and gastrointestinal tracts. Monocytes are the precursors of macrophages. They are larger blood cells, which after attaining maturity in the bone marrow, enter the blood circulation where they stay for 24-36 hours. Then they migrate into the connective tissue, where they become macrophages and move within the tissues. In the presence of an inflammation site, monocytes quickly migrate from the blood vessel and start an intense phagocytory activity. The role of these cells is not solely in phagocytosis because they have also have an intense secretory activity. They produce substances which have defensive functions such as lysozime, interferons and other substances which modulate the functionality of other cells. Macrophages cooperate in the immune defense. They expose molecules of digested bodies on the membrane and present them to more specialized cells, such as B and T lymphocytes Test- No. 1 Enumerate the leucocytes cells and what is the function of leukocytes cells 6 unit three 1-3 - Platelets (thrombocytes) - help in blood clotting. The primary function of platelets, or thrombocytes, is blood clotting. Platelets are much smaller in size than the other blood cells. The normal platelet count is 150,000-350,000 per microliter of blood They group together to form clumps, or a plug, in the hole of a vessel to stop bleeding. 2-3 Blood Clotting When blood vessels are cut or damaged, the loss of blood from the system must be stopped before shock and possible death occur. This is accomplished by solidification of the blood, a process called coagulation or clotting. A blood clot consists of a plug of platelets enmeshed in a network of insoluble fibrin molecules. Platelet aggregation and fibrin formation both require the proteolytic enzyme thrombin. Clotting also requires: calcium ions (Ca2+)(which is why blood banks use a chelating agent to bind the calcium in donated blood so the blood will not clot in the bag). about a dozen other protein clotting factors. Most of these circulate in the blood as inactive precursors. They are activated by proteolytic cleavage becoming, in turn, active proteases for other factors in the system. 7 3-3 Initiating the Clotting Process Damaged cells display a surface protein called tissue factor (TF) Tissue factor binds to activated Factor 7. The TF-7 heterodimer is a protease with two substrates: o Factor 10 and o Factor 9 o Let's follow Factor 10 first. Factor 10 binds and activates Factor 5. This heterodimer is called prothrombinase because it is a protease that converts prothrombin (also known as Factor II) to thrombin. Thrombin has several different activities. Two of them are: o proteolytic cleavage of fibrinogen (aka "Factor I") to form: soluble molecules of fibrin and a collection of small fibrinopeptides o activation of Factor 13 which forms covalent bonds between the soluble fibrin molecules converting them into an insoluble meshwork — the clot. (Thrombin and activated Factors 10 ("Xa") and 11 ("XIa") are serine proteases) 8 4-3 Amplifying the Clotting Process The clotting process also has several positive feedback loops which quickly magnify a tiny initial event into what may well be a lifesaving plug to stop bleeding. The TF-7 complex (which started the process) also activates Factor 9. o Factor 9 binds to Factor 8, a protein that circulates in the blood stabilized by another protein, von Willebrand Factor (vWF). o This complex activates more Factor 10. As thrombin is generated, it activates more o Factor 5 o Factor 8, and o Factor 11 (all shown above with green arrows). Factor 11 amplifies the production of activated Factor 9. Thus what may have begun as a tiny, localized event rapidly expands into a cascade of activity. Test No. 1 What is the main functions of platelets Test No.2 Describe the three basic steps involved in the clotting process 9 Unit four 1-4 Anticoagulants An anticoagulant is a drug that helps prevent the clotting (coagulation) of blood. These drugs tend to prevent new clots from forming or an existing clot from enlarging. They don't dissolve a blood clot. Anticoagulants are also given to certain people at risk for forming blood clots, such as those with artificial heart valves or who have atrial fibrillation A common type of stroke is caused by a blood clot blocking blood flow to the brain. To prevent such clots, anticoagulants are often prescribed for people with conditions such as atrial fibrillation to prevent a first or recurrent stroke. Heparin and warfarin, a derivative of coumarin, are some examples of anticoagulants 2-4 Hemoglobin Hemoglobin is the protein that carries oxygen from the lungs to the tissues and carries carbon dioxide from the tissues back to the lungs. In order to function most efficiently, hemoglobin needs to bind to oxygen tightly in the oxygen-rich atmosphere of the lungs and be able to release oxygen rapidly in the relatively oxygen-poor environment of the tissues. It does this in a most elegant and intricately coordinated way. The story of hemoglobin is the prototype example of the relationship between structure and function of a protein molecules 3-4 Hemoglobin Structure A hemoglobin molecule consists of four polypeptide chains: two alpha chains, each with 141 amino acids and two beta chains, each with 146 amino acids. The protein portion of each of these chains is called "globin". The a and b globin chains are very similar in structure. In this case, a and b refer to the two types of globin. Students often confuse this with the concept of a helix and b sheet secondary structures. But, in fact, both the a and b globin chains contain primarily a helix secondary structure with no b sheets 10 A heme group is a flat ring molecule containing carbon, nitrogen and hydrogen atoms, with a single Fe2+ ion at the center. Without the iron, the ring is called a porphyrin. In a heme molecule, the iron is held within the flat plane by four nitrogen ligands from the porphyrin ring. The iron ion makes a fifth bond to a histidine side chain from one of the helices that form the heme pocket. This fifth coordination bond is to histidine 87 in the human chain and histidine 92 in the human chain. Both histidine residues are part of the F helix in each globin chain. 4-4 The Bohr Effect The ability of hemoglobin to release oxygen, is affected by pH, CO2 and by the differences in the oxygen-rich environment of the lungs and the oxygen-poor environment of the tissues. The pH in the tissues is considerably lower (more acidic) than in the lungs. Protons are generated from the reaction between carbon dioxide and water to form bicarbonate: CO2 + H20 -----------------> HCO3- + H+ This increased acidity serves a twofold purpose. First, protons lower the affinity of hemoglobin for oxygen, allowing easier release into the tissues. As all four oxygens are released, hemoglobin binds to two protons. This helps to maintain equilibrium towards the right side of the equation. This is known as the Bohr effect, and is vital in the removal of carbon dioxide as waste because CO2 is insoluble in the bloodstream. The bicarbonate ion is much more soluble, and can thereby be transported back to the lungs after being bound to hemoglobin. If hemoglobin couldn’t absorb the excess protons, the equilibrium would shift to the left, and carbon dioxide couldn’t be removed. In the lungs, this effect works in the reverse direction. In the presence of the high oxygen concentration in the lungs, the proton affinity decreases. As protons are shed, the reaction is driven to the left, and CO2 forms as an insoluble gas to be expelled from the lungs. The proton poor hemoglobin now has a greater affinity for oxygen, and the cycle continue ------------------------------------------------------------------------------------------------------Test –No.1 Define hemoglobin and describe the structure of hemoglobin Test No. 2 Define anticoagulant and give me two example of it 11 Unit five 1-5 Blood Groups Blood groups are created by molecules present on the surface of red blood cells (and often on other cells as well). 2-5 The ABO Blood Groups The ABO blood groups were the first to be discovered (in 1900) and are the most important in assuring safe blood transfusions. The table shows the four ABO phenotypes ("blood groups") present in the human population and the genotypes that give rise to them. Blood Group Antigens on RBCs Antibodies in Serum Genotypes A A Anti-B AA or AO B B Anti-A BB or BO AB A and B Neither AB O Neither Anti-A and Anti-B OO When red blood cells carrying one or both antigens are exposed to the corresponding antibodies, they agglutinate; that is, clump together. People usually have antibodies against those red cell antigens that they lack. The antigens in the ABO system are O-linked glycoproteins with their sugar residues exposed at the cell surface. The terminal sugar determines whether the antigen is A or B. The critical principle to be followed is that transfused blood must not contain red cells that the recipient's antibodies can clump. Although theoretically it is possible to transfuse group O blood into any recipient, the antibodies in the donated plasma can damage the recipient's red cells. Thus, when possible, transfusions should be done with exactly-matched blood. than "self". 12 3-5 The Rh System Rh antigens are transmembrane proteins with loops exposed at the surface of red blood cells. They appear to be used for the transport of carbon dioxide and/or ammonia across the plasma membrane. They are named for the rhesus monkey in which they were first discovered. There are a number of Rh antigens. Red cells that are "Rh positive" express the one designated D. About 15% of the population have no RhD antigens and thus are "Rh negative". The major importance of the Rh system for human health is to avoid the danger of RhD incompatibility between mother and fetus. During birth, there is often a leakage of the baby's red blood cells into the mother's circulation. If the baby is Rh positive (having inherited the trait from its father) and the mother Rh-negative, these red cells will cause her to develop antibodies against the RhD antigen. The antibodies, usually of the IgG class, do not cause any problems for that child, but can cross the placenta and attack the red cells of a subsequent Rh + fetus. This destroys the red cells producing anemia and jaundice. The disease, called erythroblastosis fetalis or hemolytic disease of the newborn, may be so severe as to kill the fetus or even the newborn infant. It is an example of an antibody-mediated cytotoxicity disorder. Other examples of antibody-mediated cytotoxicity disorders. Although certain other red cell antigens (in addition to Rh) sometimes cause problems for a fetus, an ABO incompatibility does not. Why is an Rh incompatibility so dangerous when ABO incompatibility is not? It turns out that most anti-A or anti-B antibodies are of the IgM class and these do not cross the placenta. In fact, an Rh−/type O mother carrying an Rh+/type A, B, or AB fetus is resistant to sensitization to the Rh antigen. Presumably her anti-A and anti-B antibodies destroy any fetal cells that enter her blood before they can elicit anti-Rh antibodies in her. This phenomenon has led to an extremely effective preventive measure to avoid Rh sensitization. Shortly after each birth of an Rh+ baby, the mother is given an injection of anti-Rh antibodies. The preparation is called Rh immune globulin (RhIG) or Rhogam. These passively acquired antibodies destroy any fetal cells that got into her circulation before they can elicit an active immune response in her. Rh immune globulin came into common use in the United States in 1968, and within a decade the incidence of Rh hemolytic disease became very Test No. 1 What are the types of blood groups in human Test No. 2 What is the Rh factor 13 Unit sex 1-6 Cardiovascular system The main components of the human cardiovascular system are the heart and the blood vessels. It includes: the pulmonary circulation, a "loop" through the lungs where blood is oxygenated; and the systemic circulation, a "loop" through the rest of the body to provide oxygenated blood. An average adult contains five to six quarts (roughly 4.7 to 5.7 liters) of blood, which consists of plasma, red blood cells, white blood cells, and platelets. Also, the digestive system works with the circulatory system to provide the nutrients the system needs to keep the heart pumping 2-6 The heart The heart weighs between 7 and 15 ounces (200 to 425 grams) and is a little larger than the size of your fist. By the end of a long life, a person's heart may have beat (expanded and contracted) more than 3.5 billion times. In fact, each day, the average heart beats 100,000 times, pumping about 2,000 gallons (7,571 liters) of blood. . 14 Your heart is located between your lungs in the middle of your chest, behind and slightly to the left of your breastbone (sternum). A double-layered and slightly to the left of your breastbone (sternum). A double-layered membrane called the pericardium surrounds your heart like a sac. The outer layer of the pericardium surrounds the roots of your heart's major blood vessels and is attached by ligaments to your spinal column, diaphragm, and other parts of your body. The inner layer of the pericardium is attached to the heart muscle. A coating of fluid separates the two layers of membrane, letting the heart move as it beats, yet still be attached to your body. Your heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart. The left ventricle's chamber walls are only about a half-inch thick, but they have enough force to push blood through the aortic valve and into your body. 3-6 The Heart Valves :Four types of valves regulate blood flow through your heart: The tricuspid valve regulates blood flow between the right atrium and right ventricle. The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen. The mitral valve lets oxygen-rich blood from your lungs pass from the left atrium into the left ventricle. The aortic valve opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body's largest artery, where it is delivered to the rest of your body. 4-6 The Conduction System Electrical impulses from your heart muscle (the myocardium) cause your heart to contract. This electrical signal begins in the sinoatrial (SA) node, located at the top of the right atrium. The SA node is sometimes called the heart's "natural pacemaker." An electrical impulse from this natural pacemaker travels through the muscle fibers of the atria and ventricles, causing them to contract. Although the SA node sends electrical impulses at a certain rate, your heart rate may still change depending on physical demands, stress, or hormonal factors Test No.1 Name the valves of the heart and explain the purpose of each valves 15 Unit seven 1-7 Blood vessels A VEINS ( proprieties of veins ) 1- Veins function to return poorly oxygenated blood to the heart. 2- veins tubes collapse when their lumen are not filled with blood. 3- The thick, outer-most layer of a vein is made of collagen, wrapped in bands of smooth muscle while the interior is lined with epithelial cells called intima. 4- Most veins have one-way flaps called venous valves that prevent blood from flowing back and pooling in the lower extremities due to the effects of gravity. 5- The precise location of veins is much more variable from person to person than that of arteries. B- ARTERIES ( proprieties of arteries ) 1- Arteries are blood vessels that carry blood away from the heart (as opposed to veins, blood vessels carrying blood toward the heart). All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood. 2- The artery is has three layers: A muscular middle which is very elastic and strong, an outer layer of tissue, and an inner layer of smooth epithelial cells that allow the blood to flow easily. 3- The muscular wall of the artery actually helps the heart to pump blood. When your heart beats the artery expands with blood. Because the artery keeps pace with the heart you can actually measure how many heart beats per minute you have by counting the contractions of the artery (pulse rate) 4- Arteries also deliver oxygen rich blood to the capillaries where the actual exchange of carbon dioxide and oxygen happen. C- Capillaries ( proprieties of capillaries ) 1- Capillaries are very thin, fragile blood vessels that receive oxygen-rich blood from arteries, exchange oxygen and carbon dioxide and then deliver the waste-rich blood to the veins. 2- Capillaries are only one epithelial cell thick and blood can only flow through them in a single file. The red blood cells inside the capillary release their oxygen, which passes through the wall and into the surrounding tissue. The tissue releases its waste products, e.g. carbon dioxide, which pass through the wall and into the red blood cells. The exchange occurs 16 and the waste blood is carried back to the heart and lungs through the veins. 2-7 THE BLOOD CIRCULATORY SYSTEM There are three types of blood circulatory system, two of which (systemic circulation and pulmonary circulation) depend on a pump, the heart, to push the blood around. The third type of circulation is known as a portal system. These are specialised channels that connect one capillary bed site to another but do not depend directly on a central pump. The largest of these in the human is the hepatic portal system which connects the intestines to the liver. 3-7 The systemic circulation transfers oxygenated blood from a central pump (the heart) to all of the body tissues (systemic arterial system) and returns deoxygenated blood with a high carbon dioxide content from the tissues to the central pump (systemic venous system). As briefly mentioned above the systemic circulation supplies all the body tissues, and is where exchange of nutrients and products of metabolism occurs. All the blood for the systemic circulation leaves the left side of the heart via the aorta. This large artery then divides into smaller arteries and blood is delivered to all tissues and organs. These arteries divide into smaller and smaller vessels each with its own characteristic structure and function. The smallest branches are called arterioles. The arterioles themselves branch into a number of very small thin vessels, the capillaries, and it is here that the exchange of gases, nutrients and waste products occurs. Exchange occurs by diffusion of substances down concentration and pressure gradients. The capillaries then unite to form larger vessels, venules, which in turn unite to form fewer and larger vessels, known as veins. The veins from different organs and tissues unite to form two large veins. The inferior vena cava (from the lower portion of the body) and the superior vena cava (from the head and arms), which return blood to the right side of the heart. Thus there are a number of parallel circuits within the systemic circulation. 4-7The pulmonary circulation is where oxygen and carbon dioxide exchange between the blood and alveolar air occurs. The blood leaves the right side of the heart through a single artery, the pulmonary artery, which divides into two - one branch supplying each lung. Within the lung, the arteries divide, ultimately forming arterioles and capillaries; venules and veins return blood to the left side of the heart. 5-7Portal circulation:Normally there is only one capillary bed for each branch of a circuit; however, there are a few instances where there are two capillary beds, one after each other, in series. These are known as portal systems or portal circulations. One 17 example of this is in the liver. Part of the blood supply to the liver is venous blood coming directly from the gastrointestinal tract and spleen via the hepatic portal vein. This arrangement enables the digested and absorbed substances from the gut to be transported directly to the liver, where many of the body's metabolic requirements are synthesised. Thus there are two micro-circulations in series, one in the gut and the other in the liver. The force required to move the blood through the blood vessels in the two circulations is provided by the heart, which functions as two pumps, the left side of the heart supplying the systemic circulation and the right side the pulmonary circulation. The systemic circulation is much larger than the pulmonary circulation and thus the force generated by the left side of the heart is much greater than that of the right side of the heart. However, as the circulatory system is a closed system, the volume of blood pumped through the pulmonary circulation in a given period of time must equal the volume pumped through the systemic circulation - that is, the right and left sides of the heart must pump the same amount of blood. In a normal resting adult, the average volume of blood pumped simultaneously is approximately 5 liters per min. As there are approximately 5 liters of blood in an adult, this means that the blood circulates around the body approximately once every minute. During heavy work or exercise, the volume of blood pumped by the heart can increase up to 25 liters per min . ------------------------------------------------------------------------------ Test No. 1 Enumerate the blood vessels and distinguish between them in properties Test No. 2 How many blood circulations in human body Explain one 18 Unit eight 1-8 Heart beat A heartbeat is a two-part pumping action that takes about a second. As blood collects in the upper chambers (the right and left atria), the heart's natural pacemaker (the SA node) sends out an electrical signal that causes the atria to contract. This contraction pushes blood through the tricuspid and mitral valves into the resting lower chambers (the right and left ventricles). This part of the two-part pumping phase (the longer of the two) is called diastole. The second part of the pumping phase begins when the ventricles are full of blood. The electrical signals from the SA node travel along a pathway of cells to the ventricles, causing them to contract. This is called systole. As the tricuspid and mitral valves shut tight to prevent a back flow of blood, the pulmonary and aortic valves are pushed open. While blood is pushed from the right ventricle into the lungs to pick up oxygen, oxygen-rich blood flows from the left ventricle to the heart and other parts of the body. After blood moves into the pulmonary artery and the aorta, the ventricles relax, and the pulmonary and aortic valves close. The lower pressure in the ventricles causes the tricuspid and mitral valves to open, and the cycle begins again. This series of contractions is repeated over and over again, increasing during times of exertion and decreasing while you are at rest. The heart normally beats about 60 to 80 times a minute when you are at rest, but this can vary. As you get older, your resting heart rate rises. Also, it is usually lower in people who are physically fit. 19 2-8 blood pressure Blood pressure is the pressure of the blood against the walls of the arteries. Blood pressure results from two forces. One is created by the heart as it pumps blood into the arteries and through the circulatory system. The other is the force of the arteries as they resist the blood flow. What do blood pressure numbers indicate? The higher (systolic) number represents the pressure while the heart contracts to pump blood to the body. The lower (diastolic) number represents the pressure when the heart relaxes between beats. Blood pressure changes during the day. It is lowest as you sleep and rises when you get up. It also can rise when you are excited, nervous, or active. Still, for most of your waking hours, your blood pressure stays pretty much the same when you are sitting or standing still. That level should be lower than 120/80. When the level stays high, 140/90 or higher, you have high blood pressure. With high blood pressure, the heart works harder, your arteries take a beating, and your chances of a stroke, heart attack, and kidney problems are greater. What causes it? In many people with high blood pressure, a single specific cause is not known. This is called essential or primary high blood pressure. Research is continuing to find causes. In some people, high blood pressure is the result of another medical problem or medication. When the cause is known, this is called secondary high blood pressure. What is high blood pressure? A blood pressure of 140/90 or higher is considered high blood pressure. Both numbers are important. If one or both numbers are usually high, you have high blood pressure. If you are being treated for high blood pressure, you still have high blood pressure even if you have repeated readings in the normal range. 20 3-8 Factors Affect Blood Pressure Readings? There a number of factors that will temporarily affect blood pressure. Most are short-lived and will affect your blood pressure temporarily and then blood pressure will return to resting blood pressure. Short-lived factors that may cause changes in blood pressure, both raising and lowering, include: Asleep or awake – usually lower when sleeping Body position - lying down, sitting or standing Emotional state - such as stress and anger or being relaxed Activity level - from not moving to extreme exertion Temperature – blood pressure will tend to go up when you are cold White coat hypertension – blood pressure increases in a medical setting Sleep apnea - pauses in breathing while sleeping raise blood pressure Smoking – increases blood pressure Caffeine – increases blood pressure Alcohol – increases blood pressure Of the above list, sleep apnea, smoking, alcoholism and chronic stress are the major factors that can, over extended periods of time, cause resting blood pressure to slowly increase due to the impact they have on the body. There are two levels of high blood pressure: Stage 1 and Stage 2 (see the chart below). Categories for Blood Pressure Levels in Adults* (In mmHg, millimeters of mercury) Category Systolic (Top number) Diastolic (Bottom number) Normal Less than 120 Less than 80 Prehypertension 120-139 80-89 High Blood Pressure Systolic Diastolic Stage 1 140-159 90-99 Stage 2 160 or higher 100 or higher 21 * For adults 18 and older who: Are not on medicine for high blood pressure Are not having a short-term serious illness Do not have other conditions such as diabetes and kidney disease Note: When systolic and diastolic blood pressures fall into different categories, the higher category should be used to classify blood pressure level. For example, 160/80 would be stage 2 high blood pressure. There is an exception to the above definition of high blood pressure. A blood pressure of 130/80 or higher is considered high blood pressure in persons with diabetes and chronic kidney disease -------------------------------------------------------------------------------------------------- Test No. 1 Define blood pressure and what is the normal rate of blood pressure Test No. 2 Enumerate the factor that effecting on blood pressure reading 22 Unit nine Respiratory system The primary function of the respiratory system is the supply of oxygen to the blood so this in turn delivers oxygen to all parts of the body. The respiratory system does this while breathing is taking place. During the process of breathing we inhale oxygen and exhale carbon dioxide. This exchange of gases takes place at the alveoli. The average adult's lungs contain about 600 million of these spongy, air-filled sacs that are surrounded by capillaries. The inhaled oxygen passes into the alveoli and then diffuses through the capillaries into the arterial blood. Meanwhile, the waste-rich blood from the veins releases its carbon dioxide into the alveoli. The carbon dioxide follows the same path out of the lungs when you exhale. 1-9 the principle functions of the respiratory system are: Ventilate the lungs Extract oxygen from the air and transfer it to the bloodstream Excrete carbon dioxide and water vapour Maintain the acid base of the blood inspired Air This contains approx: 79% nitrogen 20% O2 0.04% CO2 Water vapour/Trace Gases Expired Air This contains approx: 79% nitrogen 16% O2 4% CO2 Water vapour/Trace Gases 23 2-9 Structure of the respiratory System Respiration takes place with the aid of the mouth, nose, trachea, lungs, diaphragm and intercostal muscles . Oxygen enters the respiratory system through the mouth and the nose. The oxygen then passes through the larynx and the trachea. In the chest cavity, the trachea splits into two bronchi. Each bronchus then divides again forming the bronchial tubes. The bronchial tubes lead directly into the lungs where they divide into many smaller tubes which connect to tiny sacs called alveoli. 1- The lungs Structure The lungs are paired, cone-shaped organs which take up most of the space in our chests, along with the heart. Their role is to take oxygen into the body, which we need for our cells to live and function properly, and to help us get rid of carbon dioxide, which is a waste product. We each have two lungs, a left lung and a right lung. These are divided up into 'lobes', or big sections of tissue separated by 'fissures' or dividers. The right lung has three lobes but the left lung has only two, because the heart takes up some of the space in the left side of our chest. The lungs can also be divided up into even smaller portions, called 'bronchopulmonary segments'. These are pyramidal-shaped areas which are also separated from each other by membranes. There are about 10 of them in each lung. Each segment receives its own blood supply and air supply. 3-9 How they work Air enters your lungs through a system of pipes called the bronchi. These pipes start from the bottom of the trachea as the left and right bronchi and branch many times throughout the lungs, until they eventually form little thinwalled air sacs or bubbles, known as the alveoli. The alveoli are where the important work of gas exchange takes place between the air and your blood. Covering each alveolus is a whole network of little blood vessel called capillaries, which are very small branches of the pulmonary arteries. It is 24 important that the air in the alveoli and the blood in the capillaries are very close together, so that oxygen and carbon dioxide can move (or diffuse) between them. So, when you breathe in, air comes down the trachea and through the bronchi into the alveoli. This fresh air has lots of oxygen in it, and some of this oxygen will travel across the walls of the alveoli into your bloodstream. Travelling in the opposite direction is carbon dioxide, which crosses from the blood in the capillaries into the air in the alveoli and is then breathed out. In this way, you bring in to your body the oxygen that you need to live, and get rid of the waste product carbon dioxide. 4-9 Blood Supply The lungs are very vascular organs, meaning they receive a very large blood supply. This is because the pulmonary arteries, which supply the lungs, come directly from the right side of your heart. They carry blood which is low in oxygen and high in carbon dioxide into your lungs so that the carbon dioxide 25 can be blown off, and more oxygen can be absorbed into the bloodstream. The newly oxygen-rich blood then travels back through the paired pulmonary veins into the left side of your heart. From there, it is pumped all around your body to supply oxygen to cells and organs. 5-9 Functions of the lungs In addition to their function in respiration, the lungs also: alter the pH of blood by facilitating alterations in the partial pressure of carbon dioxide filter out small blood clots formed in veins filter out gas micro-bubbles occurring in the venous blood stream such as those created after scuba diving during decompression. influence the concentration of some biologic substances and drugs used in medicine in blood convert angiotensin I to angiotensin II by the action of angiotensinconverting enzyme may serve as a layer of soft, shock-absorbent protection for the heart, which the lungs flank and nearly enclose. Media: Immunoglobulin-A is secreted in the bronchial secretion and protects against respiratory infections. maintain sterility by producing mucus containing antimicrobial compounds.] Mucus contains glycoproteins, eg mucins, lactoferrin lysozyme, lactoperoxidase. We find also on the epithelium Dual oxidase proteins generating hydrogen peroxidde, useful for hypothiocyanite endogenous antimicrobial synthesis. Function not in place in cystic fibrosis patient lungs. Ciliary escalator action is an important defence system against airborne infection. The dust particles and bacteria in the inhaled air are caught in the mucous layer present at the mucosal surface of respiratory passages and are moved up towards pharynx by the rhythmic upward beating action of the cilia --------------------------------------------------------------------------------------------------Test No. 1 Enumerate the functions of the lungs Test No. 2 Comber between inspiration and expiration process Test No. 3 List the respiratory volume Note :- this test involved unit( 9,10& 11 ) 26 Unit ten 1-10 conducting air ways 1- Nose: • Olfaction (smelling) • Assists in producing sound • Warming and Humidifying. Highly vascularized mucus membrane that warms and humidifies inspired air. Without this function the trachea can become dry. • Upper one-third of the nasal cavity is lined with olfactory epithelium the lower two-thirds are lined with pseudostratified ciliated columnar epithelium. • All the way through the respiratory tract there are numerous mucous secreting goblet cells with microvilli on the surface. • Cilia plays an important role in propelling mucous and trapped particles in to the pharynx where it is swallowed or spat out. 2- Pharynx: • Extends from the base of the skull to the inferior border of the cricoids cartilage • Continuous interiorly with the trachea and posterior with the esophagus • Divided into 3 parts; Nasopharynx, Or pharynx, Laryngopharynx. • Oro and Laryngopharynx are part of the respiratory and alimentary tract and are lined with non-keratinized stratified squamous (NKSS) 3- Larynx: • Inferior end continuous with the trachea. Superior end attached to the hyoid bone and lies below the epiglottis • Protects the trachea from foreign objects and particles. • Assists in warming and humidifying incoming air • Made of cartilaginous material • The larynx is lined with NKSS epithelium as well as pseudostratified ciliated columnar epithelium • Includes; Epiglottis, Thyroid, Arytenoids and Cricoids cartilages • Vocal cords are housed in this area. Air rushing past these cords cause them to vibrate thus making sound 27 4- Trachea: • 10cm in length, 2.5cm in diameter and constructed of incomplete C-shaped hyaline cartilage. Rings are completed posteriorly by the trachealis muscle • Extends from the larynx to the carina; level with 4th and 5th thoracic vertebra 5- Bronchi: • Primary bronchi is inferior to the carina; bifurcation of the trachea. • The bronchi are similar in structure to that of the trachea and are lined with ciliated columnar epithelium. As the tubes become smaller the cartilages become irregular and also become smaller until the tubes get to 1mm, this is when the cartilage disappears. As there is no cartilage the smooth muscle becomes thicker. 6- Bronchioles: • No cartilage as the smooth muscle is thicker to help maintain the structure. • The smooth muscle is responsive to autonomic nerve stimulation • The internal walls are lined with ciliated columnar mucous membrane but as the walls extend towards the distal bronchiole this membranous layer changes to non-ciliated cuboidal-shaped cells. 7- Terminal Bronchioles: • Split into 2 or more respiratory bronchioles • Thinner walls and are lined with ciliated columnar epithelium. • Do not contain any goblet cells. • Increased numbers of clara cells that line the lumen and secrete an agent similar to surfactant 28 29 Unit eleven 1-11 breathing Air from the atmosphere passes through the conducting airway until it reaches the alveoli. The walls of the alveoli are only one cell thick and this is called the respiratory surface, which is about 70 square meters, where the exchange of gases takes place. Around the alveoli are microscopic capillaries that bring carbon dioxide from the heart via pulmonary artery and delivers oxygen back to the heart via the pulmonary vein. Gas exchange happens when there is a difference in partial pressure at the semi-permeable membrane of the alveoli (diffusion). The diffusion occurs when the higher concentration of a gas moves to the lower concentration until equilibrium is achieved Partial Pressure of Gases Deoxygenated Blood Gas Alveolar Oxygenated Blood O2 105 mmHg 40 mmHg 100 mmHg CO2 40 mmHg 44 mmHg 40 mmHg Using the table above, we can see that oxygenated blood from the alveolar will diffuse across the semi-permeable membrane and replace the lower concentration of 02 in the deoxygenated blood. The higher concentration of C02 will diffuse in the same way. This is because Dalton’s law states ‘each gas exerts its own pressure in proportion to it’s concentration in a mixture’. Inhaled 02 has a higher percentage than exhaled 02, its pressure is higher at 100mmHg compared to the 40mmHg of lower percentage from the deoxygenated blood. The reverse of this applies to the C02 because the percentage breathed in is lower than that which is exhaled. 2-11 inspiration and expiration process Inspiration- Diaphragm and intercostals muscles contract. The diaphragm moves downwards. The intercostals muscles make the rib cage move upwards. These two processes increase the volume of the thoracic cavity and also reduces the air pressure to below atmospheric pressure allowing air to rush into the airways then into the alveoli. 30 Expiration is the opposite of inspiration as in the diaphragm and intercostals muscles relax, this allows the diaphragm to move upwards and the intercostals muscles let the rib cage relax to its resting state. The volume within the thoracic cavity now decreases. This decrease in volume now causes an increase in pressure above atmospheric pressure which forces air out up the airway . 3-11 Central Control Breathing is clearly an involuntary process (you don't have to think about it), and like many involuntary processes (such as heart rate) it is controlled by a region of the brain called the medulla. The medulla and its nerves are part of the autonomic nervous system (i.e. involuntary). The region of the medulla that controls breathing is called the respiratory centre. The main centers are the apneustic centre, which enhances inspiration, and the pneumotaxic centre, which terminates inspiration. The respiratory centre transmits regular nerve impulses to the diaphragm and intercostal muscles to cause inhalation. Stretch receptors in the alveoli and bronchioles detect inhalation and send inhibitory signals to the respiratory centre to cause exhalation. This negative feedback system in continuous and prevents damage to the lungs Ventilation is also under voluntary control from the cortex, the voluntary part of the brain. This allows you to hold your breath or blow out candles, but it can be overruled by the autonomic system in the event of danger. For example if 31 you hold your breath for a long time, the carbon dioxide concentration in the blood increases so much that the respiratory centre forces you to gasp and take a breath. Peripheral Chemoreceptor A chemoreceptor, is a cell or group of cells that transducer a chemical signal into an action potential Chemo receptors in the carotid arteries and aorta, detect the levels of carbon dioxide in the blood. To do this, they monitor the concentration of hydrogen ions in the blood, which increases the pH of the blood, as a direct consequence of the raised carbon dioxide concentration. The response is that the inspiratory control from the apneustic centre, sends nervous impulses to the external intercostals muscles and the diaphragm, via the phrenic nerve to increase breathing rate and the volume of the lungs during inhalation. 4-11 Respiratory volume Total lung capacity (TC), about six liters, is all the air the lungs can hold. Vital capacity (VC) The maximum volume of air that can be expelled at the normal rate of exhalation after a maximum inspiration Tidal volume (TV) is the amount of air breathed in or out during normal respiration. It is normally from 450 to 500 mL. Residual volume (RV) is the amount of air left in the lungs after a maximal exhalation. This averages about 1.5 L. Expiratory reserve volume (ERV) is the amount of additional air that can be breathed out after normal expiration. This is about 1.5 L. Inspiratory reserve volume similarly, is the additional air that can be inhaled after a normal tidal breath in. About 2.5 more liters can be inhaled. Functional residual capacity, (ERV + RV), is the amount of air left in the lungs after a tidal breath out. Inspiratory capacity (IC) is the volume that can be inhaled after a tidal breath out. Anatomical dead space is the volume of the airways. 32 Unit twelve Renal system 1-12 structure of renal system The renal system consists of all the organs involved in the formation and release of urine. It includes the kidneys, ureters, bladder and urethra. 1- The kidneys are bean-shaped organs which help the body produce urine to get rid of unwanted waste substances. When urine is formed, tubes called ureters transport it to the urinary bladder, where it is stored and excreted via the urethra. 2- Bladder The bladder is a pyramid-shaped organ which sits in the pelvis (the bony structure which helps form the hips). The main function of the bladder is to store urine and, under the appropriate signals, release it into a tube which carries the urine out of the body. Normally, the bladder can hold up to 500 mL of urine. The bladder has three openings: two for the ureters and one for the urethra (tube carrying urine out of the body). The bladder consists of smooth muscles. The main muscle of the bladder is called the detrusor muscle. Muscle fibres around the opening of the urethra forms a ring-like muscle that controls the passage of urine. When we want to urinate, stretch receptors in the bladder are activated, which send signals to our brain and tell us that the bladder is full. The ring-like muscle relaxes and the detrusor muscle contracts, allowing urine to flow. The blood supply of the bladder is from many blood vessels. Some of these blood vessels are named: the vesical arteries, the obturator, uterine, gluteal and vaginal arteries. In females, a venous network drains blood from the bladder arteries into the internal iliac vein. Nervous control of the bladder involves centres located in the brain and spinal cord 33 3- Urethra The male urethra is 18–20 cm long, running from the bladder to the tip of the penis. The male urethra is supplied by the inferior vesical and middle rectal arteries. The veins follow these blood vessels. The nerve supply is via the pudendal nerve. The female urethra is 4–6 cm long and 6 mm wide. It is a tube running from the bladder neck and opening into an external hole located at the top of the vaginal opening. As the female urethra is shorter than the male urethra, it is more likely to get infections from bacteria in the vagina. The female urethra is supplied by the internal pudendal and vaginal arteries. 34 2-12 structure of kidney On sectioning, the kidney has a pale outer region- the cortex- and a darker inner region- the medulla.The medulla is divided into 818 conical regions, called the renal pyramids; the base of each pyramid starts at the corticomedullary border, and the apex ends in the renal papilla which merges to form the renal pelvis and then on to form the ureter. In humans, the renal pelvis is divided into two or three spaces -the major calyces- which in turn divide into further minor calyces. The walls of the calyces, pelvis and ureters are lined with smooth muscle that can contract to force urine towards the bladder by peristalisis. The cortex and the medulla are made up of nephrons; these are the functional units of the kidney, and each kidney contains about 1.3 million of them. 35 3-12 structure of nephron The nephron is the unit of the kidney responsible for ultrafiltration of the blood and reabsorption or excretion of products in the subsequent filtrate. Each nephron is made up of: A filtering unit- the glomerulus. 125ml/min of filtrate is formed by the kidneys as blood is filtered through this sieve-like structure. This filtration is uncontrolled. The proximal convoluted tubule. Controlled absorption of glucose, sodium, and other solutes goes on in this region. The loop of Henle. This region is responsible for concentration and dilution of urine by utilising a counter-current multiplying mechanismbasically, it is water-impermeable but can pump sodium out, which in turn affects the osmolarity of the surrounding tissues and will affect the subsequent movement of water in or out of the water-permeable collecting duct. The distal convoluted tubule. This region is responsible, along with the collecting duct that it joins, for absorbing water back into the bodysimple maths will tell you that the kidney doesn't produce 125ml of urine every minute. 99% of the water is normally reabsorbed, leaving highly concentrated urine to flow into the collecting duct and then into the renal pelvis. Test No.1 Describe the structure of nepheron Test no.2 Enumerate the functions of kidney ( this test for unit 13 ) 36 Unit thirteen 1-13 functions of the kidney 1. Control of the body's water balance. The amount of water in the body must be balanced against the amount of water which we drink and the amount we lose in urine and sweat etc. 2. Regulation of blood pressure via the renin-angiotensin-aldosterone system 3. Regulation of blood electrolyte balance - Na+, Ca2+, K+ etc. 4. Excretion of metabolic wastes such as urea, creatinine and foreign substances such as drugs and the chemicals we ingest with our food 5. Help in the regulation of the body’s acid base balance 6. Regulation of red blood cell production via the hormone erythropoietin 7. Help in the production of vitamin D As this list indicates, the renal system is very important to the normal functioning of the body. 2-13 water regulations by the kidneys The water content of the body can vary depending on various factors. Hot weather and physical activity such as exercise make us sweat and so lose body fluids. Drinking tends to be at irregular intervals when socially convenient. This means that sometimes the body has too little water and needs to conserve it and sometimes too much water and needs to get rid of it. Most of the control of water conservation takes place in the distal and collecting tubules of the nephrons under control of anti-diuretic hormone, (ADH), sometimes called vasopressin. This hormone is released by the posterior pituitary under control of the hypothalamus in the mid-brain area. The hypothalamus monitors the water content of the blood. If the blood contains too little water (indicating dehydration) then more ADH is released. If the blood contains too much water (indicating over-hydration) then less ADH is released into the blood stream 37 Release of ADH from the posterior pituitary into the bloodstream ADH released from the pituitary travels in the blood stream to the peritubular capillaries of the nephron. ADH binds to receptors on the distal and collecting tubules of the nephrons which causes water channels to open in the tubule walls. This allows water to diffuse through the tubule walls into the interstitial fluid where it is collected by the peritubular capillaries. The more ADH present, the more water channels are open and the more water is reabsorbed - Figure Reabsorption of water from the filtrate under the influence of ADH Over 99% of the filtrate produced each day can be reabsorbed. The amount of water reabsorbed from the filtrate back into the blood depends on the water situation in the body. When the body is dehydrated, most of the filtrate is reabsorbed but note that even in cases of extreme of water shortage, the kidneys will continue to produce around 500 ml of urine each day in order to perform their excretory function. 38 Unit fourteen 1-14 The formation of urine Filtration ,reaborption ,and secretion. 1- Filtration Urine formation begins with the process of filtration, which goes on continually in the renal corpuscles.As blood courses through the glomeruli, much of its fluid, containing both useful chemicals and dissolved waste materials, soaks out of the blood through the membranes (by osmosis and diffusion) where it is filtered and then flows into the Bowman's capsule. This process is called glomerular filtration. The water, waste products, salt, glucose, and other chemicals that have been filtered out of the blood are known collectively as glomerular filtrate. The glomerular filtrate consists primarily of water, excess salts (primarily Na+ and K+), glucose, and a waste product of the body called urea. Urea is formed in the body to eliminate the very toxic ammonia products that are formed in the liver from amino acids. Since humans cannot excrete ammonia, it is converted to the less dangerous urea and then filtered out of the blood. Urea is the most abundant of the waste products that must be excreted by the kidneys. The total rate of glomerular filtration (glomerular filtration rate or GFR) for the whole body (i.e., for all of the nephrons in both kidneys) is normally about 125 ml per minute. That is, about 125 ml of water and dissolved substances are filtered out of the blood per minute. 2- Reabsorption Reabsorption, by definition, is the movement of substances out of the renal tubules back into the blood capillaries located around the tubules (called the peritubular copillaries). Substances reabsorbed are water, glucose and other nutrients, and sodium (Na+) and other ions. Reabsorption begins in the proximal convoluted tubules and continues in the loop of Henle, distal convoluted tubules, and collecting tubules (Figure 3). Let's discuss for a moment the three main substances that are reabsorbed back into the bloodstream. Large amounts of water - more than 178 liters per day - are reabsorbed back into the bloodstream from the proximal tubules because the physical forces acting on the water in these tubules actually push most of the water back into the blood capillaries. In other words, about 99% of the 180 liters of water that leave the blood each day by glomerular filtration returns to the blood from the proximal tubule through the process of passive reabsorption. The nutrient glucose (blood sugar) is entirely reabsorbed back into the blood from the proximal tubules. In fact, it is actively transported out of the tubules and into the peritubular capillary blood. None of this valuable nutrient is wasted by being lost in the urine. However, even when the kidneys are operating at peak efficiency, the nephrons can reabsorb only so much sugar and water. Their limitations are dramatically illustrated in cases of diabetes mellitus, a disease which causes the amount of sugar in the blood to rise far 39 above normal. As already mentioned, in ordinary cases all the glucose that seeps out through the glomeruli into the tubules is reabsorbed into the blood. But if too much is present, the tubules reach the limit of their ability to pass the sugar back into the bloodstream, and the tubules retain some of it. It is then carried along in the urine, often providing a doctor with her first clue that a patient has diabetes mellitus. The value of urine as a diagnostic aid has been known to the world of medicine since as far back as the time of Hippocrates. Since then, examination of the urine has become a regular procedure for physicians as well as scientists. Sodium ions (Na+) and other ions are only partially reabsorbed from the renal tubules back into the blood. For the most part, however, sodium ions are actively transported back into blood from the tubular fluid. The amount of sodium reabsorbed varies from time to time; it depends largely on how much salt we take in from the foods that we eat. (As stated earlier, sodium is a major component of table salt, known chemically as sodium chloride.) As a person increases the amount of salt taken into the body, that person's kidneys decrease the amount of sodium reabsorption back into the blood. That is, more sodium is retained in the tubules. Therefore, the amount of salt excreted in the urine increases. The process works the other way as well. The less the salt intake, the greater the amount of sodium reabsorbed back into the blood, and the amount of salt excreted in the urine decreases. 3- secreation Now, let's describe the third important process in the formation of urine. Secretion is the process by which substances move into the distal and collecting tubules from blood in the capillaries around these tubules. In this respect, secretion is reabsorption in reverse. Whereas reabsorption moves substances out of the tubules and into the blood, secretion moves substances out of the blood and into the tubules where they mix with the water and other wastes and are converted into urine. These substances are secreted through either an active transport mechanism or as a result of diffusion across the membrane. Substances secreted are hydrogen ions (H+), potassium ions (K+), ammonia (NH3), and certain drugs. Kidney tubule secretion plays a crucial role in maintaining the body's acid-base balance, another example of an important body function that the kidney participates in. Summary In summary, three processes occurring in successive portions of the nephron accomplish the function of urine formation: 1. Filtration of water and dissolved substances out of the blood in the glomeruli and into Bowman's capsule; 2. Reabsorption of water and dissolved substances out of the kidney tubules back into the blood (note that this process prevents substances needed by the body from being lost in the urine); 3. Secretion of hydrogen ions (H+), potassium ions (K+), ammonia (NH3), and certain drugs out of the blood and into the kidney tubules, where they are eventually eliminated in the urine. 40 2-14 the urine is the fluid excreted by the kidneys. It consists of water, carrying in solution the body's waste products such as urea, uric acid, creatinine, organic acids, and also other solutes such as Na+, K+, Ca2+, Mg2+, Cl-, the body fluid concentrations of which are regulated by the kidneys. After being produced by the kidneys, urine passes along the ureters to be stored in the bladder, until it is allowed to flow out of the body through the urethra, in the process of micturition (urination). The smooth muscle of the bladder forms an internal sphincter at its junction with the urethra, and further along the urethra is the voluntary-control external sphincter. The bladder begins to contract (micturition reflex), and produces the desire to urinate, when its volume exceeds about 200 ml. However, if we do not relax the external sphincter, the contractions subside, but return with increasing force and frequency as the bladder continues to fill. When the bladder volume is about 500 ml the micturition reflex may force open the internal sphincter and lead to a reflex relaxation of the external sphincter, so that urination occurs involuntarily. Voluntary urination involves relaxation of the external sphincter and tensing of the abdominal muscles to increase abdominal pressure and compress the bladder, to initiate bladder contraction and relaxation of the internal sphincter. Most people excrete about 1.5 litres of urine per day, but the volume can range (in healthy adults) from 400 ml up to about 25 litres, depending on fluid intake. In renal failure, there may be no urine production, and in the rare condition of untreated diabetes insipidus, the urine volume is consistently 25 litres/day. Urine is termed ‘dilute’ if its solute concentration (osmolality) is lower than that of the blood plasma, and ‘concentrated’ if its solute concentration is greater than that of the plasma. Humans who are maximally conserving water — when their kidneys are reabsorbing as much as possible — can produce urine with a solute concentration (osmolality) about five times that of blood plasma. Many other animals can conserve water much more effectively. For example, cats, dogs, and rats can produce urine of ten times the plasma osmolality, and gerbils twenty times! 41 When voided, urine is normally sterile and clear, although it has a yellow colour due to the presence of pigments. However, small amounts of particulate matter such as epithelial cells and lipids may be present; these are ‘casts’. Protein is not normally filtered from the blood plasma by the kidneys, so protein in the urine — proteinuria — is generally indicative of damage to the glomeruli, at the blind inner ends of the kidney tubules, where filtration occurs. The urine may also appear to contain blood (haematuria). This may be due to haemolysis in the bloodstream (breakdown of red cells) so that some haemoglobin is released from them and excreted, or it may be due to the presence of whole red cells, as a result of bleeding in the kidneys or urinary tract. Test No. 1 What is urine ? where and how it formed Test No. 2 What is micturition ? how is it controlled ? 42 Unit fifteen 1-15 Kidney Stones In some people, chemicals crystallize in the urine and form the beginning, of a kidney stone. These stones are very tiny when they form, smaller than a grain of sand, but gradually can grow over time to a 1/10 of an inch or larger. Urolithiasis is the term that refers to the presence of stones in the urinary tract, while nephrolithiasis refers to kidney stones. The size of the stone doesn't matter as much as where it is located. When the stone sits in the kidney, it rarely causes problems, but when it falls into the ureter, it acts like a dam. As the kidney continues to function and make urine, pressure builds up behind the stone and causes the kidney to swell. This pressure is what causes the pain of a kidney stone, but it also helps push the stone along the course of the ureter. When the stone enters the bladder, the obstruction in the ureter is relieved and the symptoms of a kidney stone are resolved. 2-15 kidney stones causes 1- Heredity: Some people are more susceptible to forming kidney stones, and heredity may play a role. The majority of kidney stones are made of calcium, and hypercalciuria (high levels of calcium in the urine) is a risk factor. The predisposition to high levels of calcium in the urine may be passed on from generation to generation. Some rare hereditary diseases also predispose some people to form kidney stones. Examples include people with renal tubular acidosis and people with problems metabolizing a variety of chemicals including cystine (an amino acid), oxalate, (a type of salt), and uric acid (as in gout). 2- Geographical location: There may be a geographic predisposition to form kidney stones. There are regional "stone belts," with people living in the southern United States, having an increased risk of stone formation. The hot climate and poor fluid intake may cause people to be relatively dehydrated, with their urine becoming more concentrated and allowing chemicals to come in closer contact to form the nidus, or beginning, of a stone. 3- Diet: Diet may or may not be an issue. If a person is susceptible to forming stones, then foods high in calcium may increase the risk; however, if a person isn't susceptible to forming stones, diet will not change that risk. 4- Medications: People taking diuretics (or "water pills") and those who consume excess calcium-containing antacids can increase the amount of 43 calcium in their urine and potentially increase their risk of forming stones. Taking excess amounts of vitamins A and D are also associated with higher levels of calcium in the urine. Patients with HIV who take the medication indinavir (Crixivan) can form indinavir stones. Other commonly prescribed medications associated with stone formation include dilantin and antibiotics like ceftriaxone (Rocephin) and ciprofloxacin (Cipro). 5- Underlying illnesses: Some chronic illnesses are associated with kidney stone formation, including cystic fibrosis, renal tubular acidosis, and inflammatory bowel disease. Test no. 1 Enumerate the causes of Kidney stones 44 Unit sixteen The kidney effects on blood pressure 1-16 RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM The long-term control of blood pressure is via the renin-angiotensinaldosterone (RAA) system. This system is also one of the body's compensatory mechanisms to a fall in blood pressure. The kidneys release renin into the bloodstream and this converts angiotensinogen to angiotensin I which in turn is converted to angiotensin II by angiotensin converting enzyme in the capillaries of the lungs. Under the influence of Angiotensin II, aldosterone levels increase. This increases blood sodium levels by decreasing the amount of salt excreted by the kidneys. Retaining salt instead of excreting it into urine increases the osmolarity of the blood and so the blood volume. As the volume increases, so does the blood pressure. Angiotensin II is also a potent vasoconstrictor which raises blood pressure by increasing vascular resistance -. The Renin, angiotensin, aldosterone response to a fall in blood pressure 45 2-16 acid base balance The body controls the acidity of the blood very carefully because any deviation from the normal pH of around 7.4 can cause problems - especially with the nervous system. Deviations in pH can occur due to trauma or diseases such as diabetes, pneumonia and acute asthma. The mechanisms that resist and redress pH change are... 1. Minor changes in pH are resisted by plasma proteins acting as buffers in the blood. 2. Adjustment to the rate and depth of breathing. An increase in acidity (decrease in pH) increases the rate and depth of breathing which gets rid of carbon dioxide from the blood and so reduces acidity. 3. The kidneys respond to changes in blood pH by altering the excretion of acidic or basic ions in the urine. If the body becomes more acidic, the kidneys excrete acidic hydrogen ions (H+) and conserve basic bicarbonate ions (HCO3). If the body becomes more basic, the kidneys excrete basic bicarbonate ions and conserve acidic hydrogen ions. Together, these three mechanisms maintain tight control over the pH of the body. 46 Unit seventeen Digestive system The Structure and Function of the Digestive System The digestive system is a series of hollow organs joined in a long tube from the mouth to the anus. The function of the digestive system is digestion and absorption. Digestion is the breakdown of food into small molecules, which are then absorbed into the body. The digestive system is divided into two major parts: 1-17 Parts of the digestive system Mouth The mouth is the beginning of the digestive tract; and, in fact, digestion starts here when taking the first bite of food. Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down. pharynx the pharynx opens into the larynx and esophagus. It is divided into three regions according to location: the nasopharynx, the oropharynx, and the laryngopharynx or hypopharynx. Esophagus Located in your throat near your trachea (windpipe), the esophagus receives food from your mouth when you swallow. By means of a series of muscular contractions called peristalsis, the esophagus delivers food to your stomach. Stomach The stomach is a hollow organ, or "container," that holds food while it is being mixed with enzymes that continue the process of breaking down food into a usable form. Cells in the lining of the stomach secrete a strong acid and powerful enzymes that are responsible for the breakdown process. When the contents of the stomach are sufficiently processed, they are released into the small intestine. Small intestine Made up of three segments — the duodenum, jejunum, and ileum — the small intestine is a 22-foot long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver. Peristalsis also is at work in this organ, moving food through and mixing it with digestive secretions from the pancreas and liver. The duodenum is largely responsible for the continuous breaking-down process, with the jejunum and ileum mainly responsible for absorption of nutrients into the bloodstream. Contents of the small intestine start out semi-solid, and end in a liquid form after passing through the organ. Water, bile, enzymes, and mucous contribute 47 to the change in consistency. Once the nutrients have been absorbed and the leftover-food residue liquid has passed through the small intestine, it then moves on to the large intestine, or colon. Pancreas The pancreas secretes digestive enzymes into the duodenum, the first segment of the small intestine. These enzymes break down protein, fats, and carbohydrates. The pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the chief hormone for metabolizing sugar. Liver The liver has multiple functions, but its main function within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat. In addition, the liver is the body’s chemical "factory." It takes the raw materials absorbed by the intestine and makes all the various chemicals the body needs to function. The liver also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs. Gallbladder The gallbladder stores and concentrates bile, and then releases it into the duodenum to help absorb and digest fats. Colon (large intestine) The colon is a 6-foot long muscular tube that connects the small intestine to the rectum. The large intestine is made up of the cecum, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum. The appendix is a small tube attached to the cecum. The large intestine is a highly specialized organ that is responsible for processing waste so that emptying the bowels is easy and convenient. Stool, or waste left over from the digestive process, is passed through the colon by means of peristalsis, first in a liquid state and ultimately in a solid form. As stool passes through the colon, water is removed. Stool is stored in the sigmoid (S-shaped) colon until a "mass movement" empties it into the rectum once or twice a day. It normally takes about 36 hours for stool to get through the colon. The stool itself is mostly food debris and bacteria. These bacteria perform several useful functions, such as synthesizing various vitamins, processing waste products and food particles, and protecting against harmful bacteria. When the descending colon becomes full of stool, or feces, it empties its contents into the rectum to begin the process of elimination. Rectum The rectum (Latin for "straight") is an 8-inch chamber that connects the colon to the anus. It is the rectum's job to receive stool from the colon, to let the person know that there is stool to be evacuated, and to hold the stool until evacuation happens. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not. If they can, the sphincters relax and the rectum contracts, disposing its contents. If the contents cannot be disposed, the sphincter contracts and the rectum accommodates so that the sensation temporarily goes away. 48 Anus The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external). The lining of the upper anus is specialized to detect rectal contents. It lets you know whether the contents are liquid, gas, or solid. The anus is surrounded by sphincter muscles that are important in allowing control of stool. The pelvic floor muscle creates an angle between the rectum and the anus that stops stool from coming out when it is not supposed to. The internal sphincter is always tight, except when stool enters the rectum. It keeps us continent when we are asleep or otherwise unaware of the presence of stool. When we get an urge to go to the bathroom, we rely on our external sphincter to hold the stool until reaching a toilet, where it then relaxes to release the contents. 2-17 functions of stomach The primary functions of the stomach are digestion and killing bacteria and breaking down food releasing to the small intestine while maintaining a constant release rate of material from the stomach to the small intestine. The pH inside of the stomach is maintained at very acidic levels which help the digestive enzymes like pepsin break down the material further so it can be moved to the small intestine successfully. Finally, the stomach is also responsible for helping the small intestine absorb vitamins. 3-17 Function of the Small Intestine The small intestine is responsible for absorbing most of the nutrients found within your food. By the time ingested food reaches the small intestine, it has been mechanically broken down into a liquid. As this liquid flows across the inner surface of the small intestine (which has many small folds to increase the surface area), nutrients within the food come into contact with the many small blood vessels which surround the small intestine. This blood then leaves the small intestine, carrying away nutrients, water electrolytes, vitamins, minerals, fats and medications to the entire body. It can take three to six hours for a meal to pass from one end of the small intestine to the other, and that is dependent on the makeup of the food passing through; meals containing a lot of fiber move more quickly. 49 Unit eighteen Accessory glands of the digestive system 1-18 salivary glands The glands are found in and around your mouth and throat. We call the major salivary glands the parotid, submandibular, and sublingual glands. They all secrete saliva into your mouth, the parotid through tubes that drain saliva, called salivary ducts, near your upper teeth, submandibular under your tongue, and the sublingual through many ducts in the floor of your mouth. Besides these glands, there are many tiny glands called minor salivary glands located in your lips, inner cheek area (buccal mucosa), and extensively in other linings of your mouth and throat. 2-18 Functions of salivary glands Salivary glands produce the saliva used to moisten your mouth, initiate digestion, and help protect your teeth from decay. As a good health measure, it is important to drink lots of liquids daily. Dehydration is a risk factor for salivary gland disease. 3-18 The Liver The liver is the largest glandular organ of the body. It weighs about 3 lb (1.36 kg). It is reddish brown in color and is divided into four lobes of unequal size and shape. The liver lies on the right side of the abdominal cavity beneath the diaphragm. Blood is carried to the liver via two large vessels called the hepatic artery and the portal vein. The heptic artery carries oxygen-rich blood from the aorta (a major vessel in the heart). The portal vein carries blood containing digested food from the small intestine. These blood vessels subdivide in the liver repeatedly, terminating in very small capillaries. Each capillary leads to a lobule. Liver tissue is composed of thousands of lobules, and each lobule is made up of hepatic cells, the basic metabolic cells of the liver. 4-18 functions of the liver 1- produce substances that break down fats. 2- convert glucose to glycogen. 3- produce urea (the main substance of urine). 4- make certain amino acids (the building blocks of proteins). 50 5- filter harmful substances from the blood (such as alcohol). 6- storage of vitamins and minerals (vitamins A, D, K and B12) . 7- maintain a proper level or glucose in the blood. 8- The liver is also responsible for producing cholesterol. It produces about 80% of the cholesterol in your body 5-18 The pancreas The pancreas is a glandular organ that secretes digestive enzymes (internal secretions) and hormones (external secretions). In humans, the pancreas is a yellowish organ about 7 inches (17.8 cm) long and 1.5 inches. (3.8 cm) wide. The pancreas lies beneath the stomach and is connected to the small intestine at the duodenum. The pancreas contains enzyme producing cells that secrete two hormones. The two hormones are insulin and glucagon. Insulin and glucagon are secreted directly into the bloodstream, and together, they regulate the level of glucose in the blood. Insulin lowers the blood sugar level and increases the amount of glucagon (stored carbohydrate) in the liver. Glucagon slowly increases the blood sugar level if it falls too low. If the insulin secreting cells do not work properly, diabetes occurs. What else does the Pancreas Do? The pancreas produces the body's most important enzymes. The enzymes are designed to digest foods and break down starches. The pancreas also helps neutralize chyme and helps break down proteins, fats and starch. Chyme is a thick semifluid mass of partly digested food that is passed from the stomach to the duodenum. If the pancreas is not working properly to neutralize chyme and break down proteins, fats and starch, starvation may occur 51 6-18 The gallbladder The gallbladder is a small pear-shaped organ that stores and concentrates bile. The gallbladder is connected to the liver by the hepatic duct. It is approximately 3 to 4 inches (7.6 to 10.2 cm) long and about 1 inch (2.5 cm) wide. What is its Function? The function of the gallbladder is to store bile and concentrate. Bile is a digestive liquid continually secreted by the liver. The bile emulsifies fats and neutralizes acids in partly digested food. A muscular valve in the common bile duct opens, and the bile flows from the gallbladder into the cystic duct, along the common bile duct, and into the duodenum (part of the small intestine). Conditions and Diseases of the gallbladder Sometimes the substances contained in bile crystallize in the gallbladder, forming gallstones. These small, hard concretions are more common in persons over 40, especially in women and the obese. They can cause inflammation of the gallbladder, a disorder that produces symptoms similar to those of indigestion, especially after a fatty meal is consumed. If a stone becomes lodged in the bile duct, it produces severe pain. Gallstones may pass out of the body spontaneously; however, serious blockage is treated by removing the gallbladder surgically. Test No 1 Trace the path of mouthful of food through the digestive tract Test no. 2 Name the accessory organs of digestion and the function of each 52 Unit nineteen 1-19 The treatment of food in the digestive system involves the following seven processes: Ingestion is the process of eating. Propulsion is the movement of food along the digestive tract. The major means of propulsion is peristalsis, a series of alternating contractions and relaxations of smooth muscle that lines the walls of the digestive organs and that forces food to move forward. Secretion of digestive enzymes and other substances liquefies, adjusts the pH of, and chemically breaks down the food. Mechanical digestion is the process of physically breaking down food into smaller pieces. This process begins with the chewing of food and continues with the muscular churning of the stomach. Additional churning occurs in the small intestine through muscular constriction of the intestinal wall. This process, called segmentation, is similar to peristalsis, except that the rhythmic timing of the muscle constrictions forces the food backward and forward rather than forward only. Chemical digestion is the process of chemically breaking down food into simpler molecules. The process is carried out by enzymes in the stomach and small intestines. Absorption is the movement of molecules (by passive diffusion or active transport) from the digestive tract to adjacent blood and lymphatic vessels. Absorption is the entrance of the digested food into the body. Defecation is the process of eliminating undigested material through the anus. 2-19 Carbohydrates digestion Carbohydrate are one of three macronutrients that provide the body with energy ( protein and fats being the other two). The chemical compounds in carbohydrates are found in both simple and complex forms, and in order for the body to use carbohydrates for energy, food must undergo digestion, absorption , and glycolysis . It is recommended that 55 to 60 percent of caloric intake come from carbohydrates. Chemical Structure Carbohydrates are a main source of energy for the body and are made of carbon, hydrogen, and oxygen . Humans obtain carbohydrates by eating foods that contain them. In order to use the energy contained in the carbohydrates, humans must metabolize , or 53 break down, the structure of the molecule in a process that is opposite that of photosynthesis. It starts with the carbohydrate and oxygen and produces carbon dioxide, water, and energy. The body utilizes the energy and water and rids itself of the carbon dioxide. 3-19 Digestion and Absorption Carbohydrates must be digested and absorbed in order to transform them into energy that can be used by the body. Food preparation often aids in the digestion process. When starches are heated, they swell and become easier for the body to break down. In the mouth, the enzyme amylase, which is contained in saliva, mixes with food products and breaks some starches into smaller units. However, once the carbohydrates reach the acidic environment of the stomach, the amylase is inactivated. After the carbohydrates have passed through the stomach and into the small intestine, key digestive enzymes are secreted from the pancreas and the small intestine where most digestion and absorption occurs. Pancreatic amylase breaks starch into disaccharides and small polysaccharides, and enzymes from the cells of the small-intestinal wall break any remaining disaccharides into their monosaccharide components. Dietary fiber is not digested by the small intestine; instead, it passes to the colon unchanged. Sugars such as galactose, glucose, and fructose that are found naturally in foods or are produced by the breakdown of polysaccharides enter into absorptive intestinal cells. After absorption, they are transported to the liver where galactose and fructose are converted to glucose and released into the bloodstream. The glucose may be sent directly to organs that need energy, it may be transformed into glycogen (in a process called glycogenesis) for storage in the liver or muscles, or it may be converted to and stored as fat. Glycolysis The molecular bonds in food products do not yield high amounts of energy when broken down. Therefore, the energy contained in food is released within cells and stored in the form of adenosine triphosphate (ATP), a high-energy compound created by cellular energy-production systems. Carbohydrates are 54 metabolized and used to produce ATP molecules through a process called glycolysis. Glycolysis breaks down glucose or glycogen into pyruvic acid through enzymatic reactions within the cytoplasm of the cells. The process results in the formation of three molecules of ATP (two, if the starting product was glucose). Without the presence of oxygen, pyruvic acid is changed to lactic acid , and the energy-production process ends. However, in the presence of oxygen, larger amounts of ATP can be produced. In that situation, pyruvic acid is transformed into a chemical compound called acetyle coenzyme A, a compound that begins a complex series of reactions in the Krebs Cycle and the electron transport system. The end result is a net gain of up to thirty-nine molecules of ATP from one molecule of glycogen (thirty-eight molecules of ATP if glucose was used). Thus, through certain systems, glucose can be used very efficiently in the 4-19 Digestion Of Protein Protein--like meat, fish, eggs, milk products, some vegetables, nuts, etc,--are long chains of amino acids. The types and arrangements of these amino acids determine the characteristics of the protein. The important digestive enzyme of the stomach, pepsin, is most active at a pH of about 2 and totally inactive at a pH above approximately 5. So, for pepsin to affect any digestive action on protein, the stomach juices must be acidic. Hydrochloric acid provides the acid environment. It is excreted by parietal cells at a pH of about 0.8, but after being mixed with the stomach contents and secretions of other glandular cells of the stomach, the pH ranges around 2 or 3. This is ideal and imperative for pepsin activity. Pepsin can essentially digest any protein in the diet. Even collagen, present, for example, in connective tissue of meat, can be digested by pepsin even though other digestive enzymes cannot affect it. Collagen fibers must be digested before the cellular protein of the meat can be digested. Lacking sufficient hydrochloric acid or pepsin, protein foods are poorly penetrated by other digestive enzymes further on and are thus poorly digested. After leaving the lower stomach, protein has been broken down from long protein molecules into shorter strings of amino acids (the building blocks of protein). As soon as these partially broken-down products enter the small intestine, they are "attacked" by pancreatic enzymes like trypsin, chymotrypsin and carboxypolypeptidase. These enzymes break down the protein even more, some to even the final stage of individual amino acids. Simply, it would be like taking apart, piece by piece, a child's toysseparating the combination of pieces. The walls of the small intestine contain and use several different enzymes for final breakdown. All the proteolytic (hastening protein breakdown) enzymes--including those of the stomach, pancreatic juice and intestinal lining--are very specific for the breaking down of individual protein combinations. A specific enzyme is 55 needed for each specific type of amino acid-linkage. That's why there are so many enzymes and why all the digestive enzymes are needed. When food is properly chewed, not eaten to excess at one time and the digestive juices are allowed to function as they should, about 98 percent of all protein is totally broken down to individual amino acids or pairs or short strings of them (polypeptides). Now the intestine can absorb them. The enzymes in the small intestine require a slightly alkaline environment to work. Since the food coming from the stomach is (or should be) an acid mix, the pancreas pours a strongly alkaline juice into the duodenum (the first part of the small intestine). Absorption Of Protein Most protein is absorbed in the form of single amino acids (the building blocks of protein), but some are absorbed as two or three amino-acid combinations. The different types of amino acids are absorbed selectively, and absorption is rapid; as soon as "free" individual amino acids are isolated or fractionated, they are absorbed. 5-19 Digestion Of Fat Fat in the diet is most commonly triglycerides or neutral fat found in both animals and plants. Cholesterol, cholesterol-compounds and phospholipids also are normal fats in foods. Because a large quantity of fat dumped into the blood stream at one time is deleterious to health and might fatally clog the circulatory system, a mechanism for retardation of stomach emptying of fat is present. When a bit of fat enters the duodenum, a chemical message is sent to the brain which then signals the stomach to cease releasing more material into the duodenum until it has taken care of the fat. Fat may stay in the stomach for four hours or longer, producing at the time a sensation of satiety (filled up) but rendering fermentation more likely. Since fermentation products irritate the stomach, and an irritated stomach subsequently evokes a greater sensation of hunger, the practice of eating fats for satiety is self-defeating. Fats clog the digestion. Much pain and indigestion have their origin with fats eaten. Only a small amount of fat is digested in the stomach by gastric lipase, a fat-splitting enzyme. Essentially, most fat digestion occurs in the small intestine. First, the fat globules must be broken into small sizes so enzymes can act. This emulsification is accomplished under the influence of bile, a secretion of the liver. Bile is stored in the gallbladder and drawn upon as needed. Bile contains a large amount of bile salts, the main function of which is to make fat globules break down. This is similar to the action of some household detergents that remove grease. The "detergent" function of bile salts is essential to fat digestion, for the lipase (fat-splitting enzymes) can "attack" the fat globules only on their surfaces. The smaller the fat particles, the better digestion. Pancreatic lipase is the most important enzyme in fat digestion. In concert, the epithelial lining of the small intestine also releases a small amount of lipase. Both lipases (pancreatic and intestinal) act to digest fat. Bile salts also form micelles, small sphericle globules. These micelles help remove the end products of fat digestion so further fat digestion can continue. These little micelles transport their cargo to the lining of the small intestine, where they're absorbed. The bile salts then return for more cargo, thus providing a "ferry service." So important are bile salts that, when in adequate supply, about 97 percent of fat is absorbed. If insufficient, only 50 to 60 percent is absorbed. 56 Absorption Of Fat Upon contacting the membrane lining of the small intestine, the end products of fat digestion become dissolved in the membrane and diffuse to the interior of the cell. As the split fat molecules enter the lining cells, intestinal lipase (enzyme) helps to further digest them. Triglycerides are formed in these cells and, along with cholesterol and phospholipids (other absorbed fat), they are given a protein coat. Thus "dressed," these final fat products pass into spaces between the cells and into the villi. Most of these fatty acids are then propelled, along with lymph (a fluid) by the lymphatic pump system. About 80 to 90 percent of digested fat is absorbed in this manner. Small amounts of fatty acids are absorbed directly into the blood going to the liver. Test no. 1 Name the food in four basic food groups Test No. 2 Explain the treatment of food in digestive system 57 Unit twenty The nervous system 1-20 The nerve cells The nervous system composed of nerve cells, or neurons: Motor Neurone: Efferent Neuron – Moving toward a central organ or point Relays messages from the brain or spinal cord to the muscles and organs Sensory Neurone: Afferent Neuron – Moving away from a central organ or point Relays messages from receptors to the brain or spinal cord 58 Neurons are similar to other cells in the body because: Interneuron (relay neurone): Relays message from sensory neurone to motor neurone Make up the brain and spinal cord There are several differences between axons and dendrites: Axons Dendrites Take information away from the cell body Bring information to the cell body Smooth Surface Generally only 1 axon per cell No ribosomes Usually many dendrites per cell Can have myelin Have ribosomes Branch further from the cell No myelin insulation body Branch near the cell body Rough Surface (dendritic spines) 59 1. Neurons are surrounded by a cell membrane. 2. Neurons have a nucleus that contains genes. 3. Neurons contain cytoplasm, mitochondria and other organelles. 4. Neurons carry out basic cellular processes such as protein synthesis and energy production. Neurons differ from other cells in the body because: 1. Neurons have specialized extensions called dendrites and axons. Dendrites bring information to the cell body and axons take information away from the cell body. 2. Neurons communicate with each other through an electrochemical process. 3. Neurons contain some specialized structures (for example, synapses) and chemicals (for example, neurotransmitters). Humans have three types of neurons: Sensory neurons have long axons and transmit nerve impulses from sensory receptors all over the body to the central nervous system. Motor neurons also have long axons and transmit nerve impulses from the central nervous system to effectors (muscles and glands) all over the body. Interneurones (also called connector neurons or relay neurons) are usually much smaller cells, with many interconnections 60 The three types of neurons are arranged in circuits and networks, the simplest of which is the reflex arc. Reflex arc can also be represented by a simple flow diagram: 2-20 The organization of nervous system . The organization of the human nervous system is shown in this diagram: 61 It is easy to forget that much of the human nervous system is concerned with routine, involuntary jobs, such as homeostasis, digestion, posture, breathing, etc. This is the job of the autonomic nervous system, and its motor functions are split into two divisions, with anatomically distinct neurones. Most body organs are innervated by two separate sets of motor neurones; one from the sympathetic system and one from the parasympathetic system. These neurones have opposite (or antagonistic) effects. In general the sympathetic system stimulates the “fight or flight” responses to threatening situations, while the parasympathetic system relaxes the body. The details are listed in this table:- Organ Sympathetic System Eye Dilates pupil Tear glands No effect Salivary glands Inhibits saliva production Lungs Dilates bronchi Heart Speeds up heart rate Gut Inhibits peristalsis Liver Stimulates glucose production Bladder Inhibits urination Parasympathetic System Constricts pupil Stimulates tear secretion Stimulates saliva production Constricts bronchi Slows down heart rate Stimulates peristalsis Stimulates bile production Stimulates urination Test No 1 List the types of neurons Test no . 2 What are the differences between axons and Dendrites 62 Unit twenty one 1-21 The central nervous system The central nervous system is made up by spinal cord and brain The spinal cord ( functions ) conducts sensory information from the peripheral nervous system (both somatic and autonomic) to the brain conducts motor information from the brain to our various effectors o skeletal muscles o cardiac muscle o smooth muscle o glands serves as a minor reflex center The brain (functions ) receives sensory input from the spinal cord as well as from its own nerves (e.g., olfactory and optic nerves) devotes most of its volume (and computational power) to processing its various sensory inputs and initiating appropriate — and coordinated — motor outputs. Both the spinal cord and the brain consist of white matter = bundles of axons each coated with a sheath of myelin gray matter = masses of the cell bodies and dendrites — each covered with synapses. In the spinal cord, the white matter is at the surface, the gray matter inside. . The Meninges Both the spinal cord and brain are covered in three continuous sheets of connective tissue, the meninges. From outside in, these are the dura mater — pressed against the bony surface of the interior of the vertebrae and the cranium the arachnoid the pia mater The region between the arachnoid and pia mater is filled with cerebrospinal fluid (CSF). 63 2-21 the spinal cord 31 pairs of spinal nerves arise along the spinal cord. These are "mixed" nerves because each contain both sensory and motor axons. However, within the spinal column, all the sensory axons pass into the dorsal root ganglion where their cell bodies are located and then on into the spinal cord itself. all the motor axons pass into the ventral roots before uniting with the sensory axons to form the mixed nerves. The spinal cord carries out two main functions: It connects a large part of the peripheral nervous system to the brain. Information (nerve impulses) reaching the spinal cord through sensory neurons are transmitted up into the brain. Signals arising in the motor areas of the brain travel back down the cord and leave in the motor neurons. The spinal cord also acts as a minor coordinating center responsible for some simple reflexes like the withdrawal reflex. The interneurons carrying impulses to and from specific receptors and effectors are grouped together in spinal tracts. Crossing Over of the Spinal Tracts Impulses reaching the spinal cord from the left side of the body eventually pass over to tracts running up to the right side of the brain and vice versa. In some cases this crossing over occurs as soon as the impulses enter the cord. In other cases, it does not take place until the tracts enter the brain itself. 3-21The Brain forebrain midbrain hindbrain. The human brain receives nerve impulses from the spinal cord and 12 pairs of cranial nerves o Some of the cranial nerves are "mixed", containing both sensory and motor axons o Some, e.g., the optic and olfactory nerves (numbers I and II) contain sensory axons only o Some, e.g. number III that controls eyeball muscles, contain motor axons only. 64 The Hindbrain The main structures of the hindbrain are the medulla oblongata pons and cerebellum Medulla oblongata The medulla looks like a swollen tip to the spinal cord. Nerve impulses arising here rhythmically stimulate the intercostal muscles and diaphragm — making breathing possible regulate heartbeat regulate the diameter of arterioles thus adjusting blood flow. The neurons controlling breathing have mu (µ) receptors, the receptors to which opiates, like heroin, bind. This accounts for the suppressive effect of opiates on breathing. Destruction of the medulla causes instant death. Pons The pons seems to serve as a relay station carrying signals from various parts of the cerebral cortex to the cerebellum. Nerve impulses coming from the eyes, ears, and touch receptors are sent on the cerebellum. The pons also participates in the reflexes that regulate breathing. The reticular formation is a region running through the middle of the hindbrain (and on into the midbrain). It receives sensory input (e.g., sound) from higher in the brain and passes these back up to the thalamus. The reticular formation is involved in sleep, arousal (and vomiting). 65 Cerebellum The cerebellum consists of two deeply-convoluted hemispheres. Although it represents only 10% of the weight of the brain, it contains as many neurons as all the rest of the brain combined. Its most clearly-understood function is to coordinate body movements. People with damage to their cerebellum are able to perceive the world as before and to contract their muscles, but their motions are jerky and uncoordinated. So the cerebellum appears to be a center for learning motor skills (implicit memory). Laboratory studies have demonstrated both long-term potentiation (LTP) and long-term depression (LTD) in the cerebellum. The Midbrain The midbrain (mesencephalon) occupies only a small region in humans). We shall look at only three features: the reticular formation: collects input from higher brain centers and passes it on to motor neurons. the substantia nigra: helps "smooth" out body movements; damage to the substantia nigra causes Parkinson's disease. the ventral tegmental area (VTA): packed with dopamine-releasing neurons that o are activated by nicotinic acetylcholine receptors and o whose projections synapse deep within the forebrain. The VTA seems to be involved in pleasure: nicotine, amphetamines and cocaine bind to and activate its dopamine-releasing neurons and this may account — at least in part (see below)— for their addictive qualities. Forebrain The human forebrain is made up of a pair of large cerebral hemispheres, called the telencephalon. Because of crossing over of the spinal tracts, the left hemisphere of the forebrain deals with the right side of the body and vice versa. a group of structures located deep within the cerebrum, that make up the diencephalon. Diencephalon We shall consider four of its structures: the Thalamus. o All sensory input (except for olfaction) passes through these paired structures on the way up to the somatic-sensory regions of the cerebral cortex and then returns to them from there. o signals from the cerebellum pass through them on the way to the motor areas of the cerebral cortex. 66 Lateral geniculate nucleus (LGN). All signals entering the brain from each optic nerve enter a LGN and undergo some processing before moving on the various visual areas of the cerebral cortex. Hypothalamus. o The seat of the autonomic nervous system. Damage to the hypothalamus is quickly fatal as the normal homeostasis of body temperature, blood chemistry, etc. goes out of control. o The source of 8 hormones, two of which pass into the posterior lobe of the pituitary gland. The Cerebral Hemispheres Each hemisphere of the cerebrum is subdivided into four lobes visible from the outside: frontal parietal occipital temporal Test no 1 Enumerate the functions of spinal cord Test no. 2 What are the parts of brain 67 Unit twenty two 1-22 Peripheral Nervous System The peripheral nervous system is divided into the following sections: Peripheral Nervous System Sensory Nervous System - sends information to the CNS from internal organs or from external stimuli. Motor Nervous System - carries information from the CNS to organs, muscles, and glands. o Somatic Nervous System - controls skeletal muscle as well as external sensory organs. o Autonomic Nervous System - controls involuntary muscles, such as smooth and cardiac muscle. Sympathetic - controls activities that increase energy expenditures. Parasympathetic - controls activities that conserve energy expenditures. 68 Sympathetic Rate increased Force increased Bronchial muscle relaxed Pupil dilation Motility reduced Sphincter closed Decreased urine secretion Structure Heart Heart Parasympathetic Rate decreased Force decreased Bronchial muscle contracted Pupil constriction Digestion increased Sphincter relaxed Increased urine secretion Lungs Eye Intestine Bladder Kidneys 69 Unit twenty three The Male reproductive system Organs of the male reproductive system are specialized for the following functions: To produce, maintain and transport sperm (the male reproductive cells) and protective fluid (semen) To discharge sperm within the female reproductive tract To produce and secrete male sex hormones The male reproductive anatomy includes internal and external structures. 1-23 The external reproductive structures Most of the male reproductive system is located outside of the man’s body. The external structures of the male reproductive system are the penis, the scrotum and the testicles. 1- Penis — The penis is the male organ for sexual intercourse. It has three parts: the root, which attaches to the wall of the abdomen; the body, and the glans, which is the cone-shaped end of the penis. The glans, which also is called the head of the penis, is covered with a loose layer of skin called foreskin. (This skin is removed in a procedure called circumcision.) The opening of the urethra, the tube that transports semen and urine, is at the tip of the glans penis. The penis also contains a number of sensitive nerve endings. Semen, which contains sperm, is expelled (ejaculated) through the end of the penis when the man reaches sexual climax (orgasm). When the penis is erect, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm. 2- Scrotum — The scrotum is the loose pouch-like sac of skin that hangs behind the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The scrotum has a protective function and acts as a climate control system for the testes. For normal sperm development, the testes must be at a temperature slightly cooler than the body temperature. Special muscles in the wall of the scrotum allow it to contract and relax, moving the testicles closer to the body for warmth and protection or farther away from the body to cool the temperature. 3-Testicles (testes) — The testes are oval organs about the size of large olives that lie in the scrotum, secured at either end by a structure called the spermatic cord. Most men have two testes. The testes are responsible for making testosterone, the primary male sex hormone, and for generating sperm. Within the testes are coiled masses of tubes called seminiferous tubules. 70 These tubules are responsible for producing the sperm cells through a process called spermatogenesis. 4-Epididymis — The epididymis is a long, coiled tube that rests on the backside of each testicle. It functions in the transport and storage of the sperm cells that are produced in the testes. It also is the job of the epididymis to bring the sperm to maturity, since the sperm that emerge from the testes are immature and incapable of fertilization. During sexual arousal, contractions force the sperm into the vas deferens. 2-23 The internal reproductive organs The internal organs of the male reproductive system, also called accessory organs, include the following: 1. Vas deferens — The vas deferens is a long, muscular tube that travels 2. 3. 4. 5. 6. from the epididymis into the pelvic cavity, to just behind the bladder. The vas deferens transports mature sperm to the urethra in preparation for ejaculation. Ejaculatory ducts — These are formed by the fusion of the vas deferens and the seminal vesicles. The ejaculatory ducts empty into the urethra. Urethra — The urethra is the tube that carries urine from the bladder to outside of the body. In males, it has the additional function of expelling (ejaculating) semen when the man reaches orgasm. When the penis is erect during sex, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm. Seminal vesicles — The seminal vesicles are sac-like pouches that attach to the vas deferens near the base of the bladder. The seminal vesicles produce a sugar-rich fluid (fructose) that provides sperm with a source of energy and helps with the sperms’ motility (ability to move). The fluid of the seminal vesicles makes up most of the volume of a man’s ejaculatory fluid, or ejaculate. Prostate gland — The prostate gland is a walnut-sized structure that is located below the urinary bladder in front of the rectum. The prostate gland contributes additional fluid to the ejaculate. Prostate fluids also help to nourish the sperm. The urethra, which carries the ejaculate to be expelled during orgasm, runs through the center of the prostate gland. Bulbourethral glands — The bulbourethral glands, or Cowper’s glands, are pea-sized structures located on the sides of the urethra just below the prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra. This fluid serves to lubricate the urethra and to neutralize any acidity that may be present due to residual drops of urine in the urethra. 3-23 How does the male reproductive system function? The entire male reproductive system is dependent on hormones, which are chemicals that stimulate or regulate the activity of cells or organs. The primary hormones involved in the functioning of the male reproductive system are follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone. 71 FSH and LH are produced by the pituitary gland located at the base of the brain. FSH is necessary for sperm production (spermatogenesis), and LH stimulates the production of testosterone, which is necessary to continue the process of spermatogenesis. Testosterone also is important in the development of male characteristics, including muscle mass and strength, fat distribution, bone mass and sex drive. Does a man go through menopause? Menopause is a term used to describe the end of a woman's normal menstrual function. Female menopause is characterized by changes in hormone production. The testes, unlike the ovaries, do not lose the ability to make hormones. If a man is healthy, he may be able to make sperm well into his 80s or longer. On the other hand, subtle changes in the function of the testes may occur as early as 45 to 50 years of age, and more dramatically after the age of 70. For many men, hormone production may remain normal into old age, while others may have declining hormone production earlier on, sometimes as a result of an illness, such as diabetes. Test no. 1 Enumerate the internal organs of male reproductive system 72 Unit twenty four The female reproductive system 1-24 functions 1- It produces the female egg cells necessary for reproduction, called the ova or oocytes. 2- transport the ova to the site of fertilization. 3- Conception, the fertilization of an egg by a sperm, normally occurs in the fallopian tubes. 4- After conception, the uterus offers a safe and favorable environment for a baby to develop before it is time for it to make its way into the outside world. 5- If fertilization does not take place, the system is designed to menstruate (the monthly shedding of the uterine lining). 6- the female reproductive system produces female sex hormones that maintain the reproductive cycle. During menopause the female reproductive system gradually stops making the female hormones necessary for the reproductive cycle to work. When the body no longer produces these hormones a woman is considered to be menopausal. 2-24 female reproductive anatomy includes internal and external structures. 1- external reproductive organs The function of the external female reproductive structures (the genital) is twofold: To enable sperm to enter the body and to protect the internal genital organs from infectious organisms. The main external structures of the female reproductive system include: Labia majora: The labia majora enclose and protect the other external reproductive organs Labia minora: Literally translated as "small lips," the labia minora can be very small or up to 2 inches wide. They lie just inside the labia majora, and surround the openings to the vagina (the canal that joins the lower part of the uterus to the outside of the body) and urethra (the tube that carries urine from the bladder to the outside of the body). Bartholin’s glands: These glands are located next to the vaginal opening and produce a fluid (mucus) secretion. Clitoris: The two labia minora meet at the clitoris, a small, sensitive protrusion that is comparable to the penis in males. The clitoris is covered by a fold of skin, called the prepuce, 73 2- The internal reproductive organs include: Vagina: The vagina is a canal that joins the cervix (the lower part of uterus) to the outside of the body. It also is known as the birth canal. Uterus ;- The uterus is a hollow, pear-shaped organ that is the home to a developing fetus. The uterus is divided into two parts: the cervix, which is the lower part that opens into the vagina, and the main body of the uterus, called the corpus. The corpus can easily expand to hold a developing baby. A channel through the cervix allows sperm to enter and menstrual blood to exit. Ovaries: The ovaries are small, oval-shaped glands that are located on either side of the uterus. The ovaries produce eggs and hormones. Fallopian tubes: These are narrow tubes that are attached to the upper part of the uterus and serve as tunnels for the ova (egg cells) to travel from the ovaries to the uterus. Conception, the fertilization of an egg by a sperm, normally occurs in the fallopian tubes. The fertilized egg then moves to the uterus, where it implants to the uterine wall. 3-24 What happens during the menstrual cycle? Females of reproductive age (anywhere from 11-16 years) experience cycles of hormonal activity that repeat at about one-month intervals. (Menstru means "monthly"; hence the term menstrual cycle.) With every cycle, a woman’s body prepares for a potential pregnancy, whether or not that is the woman’s intention. The term menstruation refers to the periodic shedding of the uterine lining. The average menstrual cycle takes about 28 days and occurs in phases: the follicular phase, the ovulatory phase (ovulation), and the luteal phase. There are four major hormones (chemicals that stimulate or regulate the activity of cells or organs) involved in the menstrual cycle: follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone. Follicular phase This phase starts on the first day of your period. During the follicular phase of the menstrual cycle, the following events occur: Two hormones, follicle stimulating hormone (FSH) and luteinizing hormone (LH) are released from the brain and travel in the blood to the ovaries. The hormones stimulate the growth of about 15-20 eggs in the ovaries each in its own "shell," called a follicle. These hormones (FSH and LH) also trigger an increase in the production of the female hormone estrogen. As estrogen levels rise, like a switch, it turns off the production of follicle-stimulating hormone. This careful balance of hormones allows 74 the body to limit the number of follicles that complete maturation, or growth. As the follicular phase progresses, one follicle in one ovary becomes dominant and continues to mature. This dominant follicle suppresses all of the other follicles in the group. As a result, they stop growing and die. The dominant follicle continues to produce estrogen. Ovulatory phase The ovulatory phase, or ovulation, starts about 14 days after the follicular phase started. The ovulatory phase is the midpoint of the menstrual cycle, with the next menstrual period starting about 2 weeks later. During this phase, the following events occur: The rise in estrogen from the dominant follicle triggers a surge in the amount of luteinizing hormone that is produced by the brain. This causes the dominant follicle to release its egg from the ovary. As the egg is released (a process called ovulation) it is captured by finger-like projections on the end of the fallopian tubes (fimbriae). The fimbriae sweep the egg into the tube. Also during this phase, there is an increase in the amount and thickness of mucus produced by the cervix (lower part of the uterus.) If a woman were to have intercourse during this time, the thick mucus captures the man's sperm, nourishes it, and helps it to move towards the egg for fertilization. Luteal phase The luteal phase begins right after ovulation and involves the following processes: Once it releases its egg, the empty follicle develops into a new structure called the corpus luteum. The corpus luteum secretes the hormones estrogen and progesterone. Progesterone prepares the uterus for a fertilized egg to implant. If intercourse has taken place and a man's sperm has fertilized the egg (a process called conception), the fertilized egg (embryo) will travel through the fallopian tube to implant in the uterus. The woman is now considered pregnant. If the egg is not fertilized, it passes through the uterus. Not needed to support a pregnancy, the lining of the uterus breaks down and sheds, and the next menstrual period begins. How many eggs does a woman have? During fetal life, there are about 6 million to 7 million eggs. From this time, no new eggs are produced. Test No. 1 Explain the functions of female reproductive system 75 Unit twenty five 1-25 The endocrine glands Glands are small but powerful organs that are located throughout the body. They control very important body functions by releasing hormones. Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct. The hypothalamus is a neuroendocrine organ. Other organs which are not so well known for their endocrine activity include the stomach, which produces such hormones as ghrelin 76 The following list of glands make up the endocrine system. Pituitary Gland Thymus Pineal Gland Testes Ovaries Thyroid Adrenal Glands Parathyroid Pancreas 2-25 Pituitary Gland The pituitary gland is sometimes called the "master gland" because of its great influence on the other body organs. Its function is complex and important for overall well-being. The pituitary gland is divided into two parts, front (anterior) and back (posterior). The anterior pituitary produces several types of hormones: Prolactin or PRL - PRL stimulates milk production from a woman's breasts after childbirth Growth hormone or GH - GH stimulates growth in childhood and is important for maintaining a healthy body composition. Adrenocorticotropin or ACTH - ACTH stimulates production of cortisol by the adrenal glands. Cortisol, a so-called "stress hormone," is vital to survival. It helps maintain blood pressure and blood glucose levels. Thyroid-stimulating hormone or TSH - TSH stimulates the thyroid gland to make thyroid hormones, which, in turn, control (regulate) the body's metabolism, energy, growth and development, and nervous system activity. Luteinizing hormone or LH - LH regulates testosterone in men and estrogen in women. Follicle-stimulating hormone or FSH - FSH promotes sperm production in men and stimulates the ovaries to release eggs (ovulate) in women. LH and FSH work together to allow normal function of the ovaries or testes. The posterior pituitary produces two hormones: Oxytocin - Oxytocin causes milk letdown in nursing mothers and contractions during childbirth. Antidiuretic hormone or ADH - ADH, also called vasopressin, is stored in the back part of the pituitary gland and regulates water balance. If this hormone is not secreted properly, this can lead to problems of sodium (salt) and water balance, and could also affect the kidneys so that they do not work as well. 77 In response to over- or underproduction of pituitary hormones, the target glands affected by these hormones can produce too many or too few hormones of their own, leading to hormone imbalance. For example, too much growth hormone can cause gigantism, or excessive growth (referred to as acromegaly in adults), while too little GH may cause dwarfism. 3-25 Thymus The thymus is a gland needed early in life for normal immune function. It is very large just after a child is born and weighs its greatest when a child reaches puberty. Then its tissue is replaced by fat. The thymus gland secretes hormones called humoral factors. These hormones help to develop the lymphoid system, which is a system throughout the body that help it to reach a mature immune response in cells to protect them from invading bodies, like bacteria. 4-25 Pineal Gland Scientists are still learning how the pineal gland works. They have found one hormone so far that is produced by this gland: melatonin. Melatonin may stop the action of (inhibit) the hormones that produce gonadotropin, which causes the ovaries and testes to develop and function. It may also help to control sleep patterns. 5-25 Testes Males have twin reproductive glands, called testes, that produce the hormone testosterone. Testosterone helps a boy develop and then maintain his sexual traits. During puberty, testosterone helps to bring about the physical changes that turn a boy into an adult male, such as growth of the penis and testes, growth of facial and pubic hair, deepening of the voice, increase in muscle mass and strength, and increase in height. Throughout adult life, testosterone helps maintain sex drive, sperm production, male hair patterns, muscle mass, and bone mass. 6-25 Ovaries The two most important hormones of a woman's twin reproductive glands, the ovaries, are estrogen and progesterone. These hormones are responsible for developing and maintaining female sexual traits, as well as maintaining a pregnancy. Along with the pituitary gonadotropins (luteinizing hormone or LH and follicle-stimulating hormone or FSH), they also control the menstrual cycle. The ovaries also produce inhibit, a protein that curbs (inhibits) the release of follicle-stimulating hormone from the anterior pituitary and helps control egg development. Test no. 1 Name the female and sex hormones and briefly describe what each does Test no. 2 Where is pineal gland located ? what is the main hormones ,and what dose it do 78 Unit twenty sex 1-26 Thyroid The thyroid is a small gland inside the neck, located in front of your breathing airway (trachea) and below your Adam's apple. The thyroid hormones control your metabolism, which is the body's ability to break down food and store it as energy and the ability to break down food into waste products with a release of energy in the process. The thyroid produces two hormones, T3 (called triiodothyronine) and T4 (called thyroxine) 2-26 Adrenal Glands Each adrenal gland is actually two endocrine organs. The outer portion is called the adrenal cortex. The inner portion is called the adrenal medulla. The hormones of the adrenal cortex are essential for life. The types of hormones secreted by the adrenal medulla are not. The adrenal cortex produces glucocorticoids (such as cortisol) that help the body control blood sugar, increase the burning of protein and fat, and respond to stressors like fever, major illness, and injury. The mineralcorticoids (such as aldosterone) control blood volume and help to regulate blood pressure by acting on the kidneys to help them hold onto enough sodium and water. The adrenal cortex also produces some sex hormones, which are important for some secondary sex characteristics in both men and women. Two important disorders caused by problems with the adrenal cortex are Cushing's syndrome and Addison's disease. Cushing's syndrome is the result of too much cortisol, and Addison's disease occurs when there is too little cortisol. The adrenal medulla produces epinephrine (adrenaline), which is secreted by nerve endings and increases the heart rate, opens airways to improve oxygen intake, and increases blood flow to muscles, usually when a person is scared, excited, or under stress. Norepinephrine also is made by the adrenal medulla, but this hormone is more related to maintaining normal activities as opposed to emergency reactions. Too much norepinephrine can cause high blood pressure. 3-26 Parathyroid Located behind the thyroid gland are four tiny parathyroid glands. These make hormones that help control calcium and phosphorous levels in the body. The parathyroid glands are necessary for proper bone development. In response to too little calcium in the diet, the parathyroid glands make parathyroid hormone, or PTH, that takes calcium from bones so that it will be available in the blood for nerve conduction and muscle contraction. If the parathyroids are removed during a thyroid operation, low blood calcium will result in symptoms such as irregular heartbeat, muscle spasms, tingling in the hands and feet, and possibly difficulty breathing. A tumor or chronic illness can cause too much 79 secretion of PTH and lead to bone pain, kidney stones, increased urination, muscle weakness, and fatigue. 4-26 Pancreas The pancreas is a large gland behind your stomach that helps the body to maintain healthy blood sugar (glucose) levels. The pancreas secretes insulin, a hormone that helps glucose move from the blood into the cells where it is used for energy. The pancreas also secretes glucagon when the blood sugar is low. Glucagon tells the liver to release glucose, stored in the liver as glycogen, into the bloodstream. Diabetes, an imbalance of blood sugar levels, is the major disorder of the pancreas. There are two types of diabetes. Type I, and Type II diabetes. Type I diabetes occurs when the pancreas does not produce enough insulin. Type II diabetes occurs when the body is resistant to the insulin in the blood). Without enough insulin to keep glucose moving through the metabolic process, the blood glucose level rises too high. In Type I diabetes, a patient must take insulin shots. In Type II diabetes, a patient may may not necessarily need insulin and can sometimes control blood sugar levels with exercise, diet and other medications. A condition called hyperinsulinism (HI) is caused by too much insulin and leads to hypoglycemia (low blood sugar). The inherited form, called congenital HI, causes severe hypoglycemia in infancy. Sometimes it can be treated with medication but often requires surgical removal of part or all of the pancreas. An insulin-secreting tumor of the pancreas, or insulinoma, is a less common cause of hypoglycemia. Symptoms of low blood sugar include anxiety, sweating, increased heart rate, weakness, hunger, and light-headedness. Low blood sugar stimulates release of epinephrine, glucagon and growth hormone, which help to return the blood sugar to normal. 5-26 exocrine glands Typical exocrine glands include sweat glands, salivary glands, mammary glands, stomach, liver, pancreas. (Example of an endocrine gland is the adrenal gland, which is found on top of the kidneys and secretes the hormone adrenaline, among others). Structure Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland. The duct portion may be branched (called compound) or unbranched (called simple). The glandular portion may be tubular, acinar, or may be a mix of the two (called tubuloacinar). If the glandular portion branches, then the gland is called a branched gland. 80 Method of secretion Exocrine glands are named apocrine gland, holocrine gland, or merocrine gland based on how their product is secreted. Apocrine glands - a portion of the plasma membrane buds off the cell, containing the secretion,an example is fat droplet secretion by mammary gland. Holocrine glands - the entire cell disintegrates to secrete its substance,an example is sebaceous glands for skin and nose. Merocrine glands - cells secrete their substances by exocytosis an example is pancreatic acinar cells. Product secreted Serous cells secrete proteins, often enzymes. Examples include chief cells and Paneth cells Mucous cells secrete mucus. Examples include Brunner's glands, esophageal glands, and pyloric glands Mixed glands secrete both protein and mucus. Examples include the salivary glands, although parotid gland is predominantly serous, the sublingual gland is predominantly mucous and the submandibular gland is both serous and mucous Test No. 1 name the two divisions of adrenal glands and describe the effects of hormones from each 81 Unit twenty seven 1-27 muscular system Over 600 skeletal muscles function for body movement through contraction and relaxation of voluntary, striated muscle fibers. These muscles are attached to bones, and are typically under conscious control for locomotion, facial expressions, posture, and other body movements. Muscles account for approximately 40 percent of body weight. The metabolism that occurs in this large mass-produces heat essential for the maintenance of body temperature. 2-27 Types of muscles There are three types of muscles 1. skeletal (or voluntary/striated) muscle, the most abundant tissue in the human body, producing movement. Each skeletal-muscle fiber is roughly cylindrical, contains many nuclei, and is crossed by alternating light and dark bands called striations. Fibers bind together, via connective tissue, into bundles; and these bundles, in turn, bind together to form muscles. Thus, skeletal muscles are composite structures composed of many muscle fibers, nerves, blood vessels, and connective tissue. Skeletal muscles are controlled by the somatic nervous system (SNS). 2. smooth (or visceral) muscle, forming the muscle layers in the walls of the digestive tract, bladder, various ducts, arteries and veins, and other internal organs. Smooth- muscle cells are elongated and thin, not striated, have only one nucleus, and interlace to form sheets rather than bundles of muscles. Smooth muscle is controlled by the autonomic nervous system (ANS). 3. cardiac (or heart) muscle, a cross between the smooth and striated muscles, comprising the heart tissue. Like smooth muscle, it is innervated by the autonomic nervous system (ANS). Test no. 1 List the types of muscles 82 Unit twenty eight 1-28 Musculoskeletal System The musculoskeletal system consists of the skeletal system -- bones and joints (union of two or more bones) -- and the skeletal muscle system (voluntary or striated muscles). These two systems work together to provide basic functions that are essential to life, including: Protection: protects the brain and internal organs Support: maintains upright posture Blood cell formation: hematopoiesis Mineral homeostasis Storage: stores fat and minerals. Leverage: A lever is a simple machine that magnifies speed of movement or force. The levers are mainly the long bones of the body and the axes are the joints where the bones meet. 2-28 Tissues There are 5 basic tissues comprising the musculoskeletal system: 1. bones, 2. ligaments (attaching bone to bone) 3. cartilage (protective gel-like subtance lining the joints and intervertebral discs), 4. skeletal muscles, and 5. tendons (attaching muscle to bone). Each of these contains various combinations of 4 connective tissue building blocks: fibroblasts - the "mother" cell, producing the other 3 connective tissue components. 83 collagen - the principal protein manufactured by the fibroblast. Organized into various configurations, these long, thin fibers intertwine to form very strong fibers which do NOT stretch. elastic fibers - highly elastic fibers, unlike collagen, particularly abundant in the walls of arteries. proteoglycans - the "ground substance," or "matrix," in which fibroblasts, collagen, and elastic fibers reside. 3-28 How We Move Skeletal muscles, attached to bone by tendons, produce movement by bending the skeleton at movable joints. The connecting tendon closest to the body or head is called the proximal attachment: this is termed the origin of the muscle. The other end, the distal attachment, is called the insertion. During contraction, the origin remains stationary and the insertion moves. The force producing the bending is always exerted as a pull by contraction, thus making the muscle shorter: Muscles cannot actively push. Reversing the direction in which a joint bends is produced by contracting a different set of muscles. For example, when one group of muscles contracts, an antagonistic group stretches, exerting an opposing pull, ready to reverse the direction of movement. The contracting unit is the muscle fiber. Muscle fibers consist of two main protein strands - actin and myosin. Where the strands overlap, the fiber appears dark. Where they do not overlap, the fiber appears light. These alternating bands of light and dark give skeletal muscle its characterisitc striated appearance. The trigger which starts contraction comes from the motor nerve attached to each muscle fiber at the motor end plate. Acetylcholine is released at the motor end plate when the electrical impulse reaches the muscle fiber. As it binds to receptors on the surface of the muscle cells, it causes the electrical impulse to be transmitted in both directions along the fiber, activating the actin and myosin strands. The strands slide past each other to flex, or to shorten, the fiber, thus producing contraction. 84 Unit twenty nine 1-29 hormones A hormone is a chemical released by a cell in one part of the body, that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. It is essentially a chemical messenger that transports a signal from one cell to another. All multicellular organisms produce hormones. Cells respond to a hormone when they express a specific receptor for that hormone. The hormone binds to the receptor protein, resulting in the activation of a signal transduction mechanism that ultimately leads to cell type-specific responses. Endocrine hormone molecules are secreted (released) directly into the bloodstream, while exocrine hormones (or ectohormones) are secreted directly into a duct, and from the duct they either flow into the bloodstream or they flow from cell to cell by diffusion . 2-29 Physiology of hormones Most cells are capable of producing one or more molecules, which act as signaling molecules to other cells, altering their growth, function, or metabolism. The classical hormones produced by cells in the endocrine glands mentioned so far in this article are cellular products, specialized to serve as regulators at the overall organism level. However they may also exert their effects solely within the tissue in which they are produced and originally released. The rate of hormone biosynthesis and secretion is often regulated by a homeostatic negative feedback control mechanism. Such a mechanism depends on factors that influence the metabolism and excretion of hormones. Thus, higher hormone concentration alone cannot trigger the negative feedback mechanism. Negative feedback must be triggered by overproduction of an "effect" of the hormone. Hormone secretion can be stimulated and inhibited by: Other hormones (stimulating- or releasing-hormones) Plasma concentrations of ions or nutrients, as well as binding globulins Neurons and mental activity Environmental changes, e.g., of light or temperature One special group of hormones is the tropic hormones that stimulate the hormone production of other endocrine glands. For example, thyroidstimulating hormone (TSH) causes growth and increased activity of another endocrine gland, the thyroid, which increases output of thyroid hormones. 85 3-29 effect of hormones Hormones have the following effects on the body: stimulation or inhibition of growth mood swings induction or suppression of apoptosis (programmed cell death) activation or inhibition of the immune system regulation of metabolism preparation of the body for mating, fighting, fleeing, and other activity preparation of the body for a new phase of life, such as puberty, parenting, and menopause control of the reproductive cycle hunger cravings A hormone may also regulate the production and release of other hormones. Hormone signals control the internal environment of the body through homeostasis. 4-29 Pharmacology Many hormones and their analogues are used as medication. The most commonly prescribed hormones are estrogens and progestagens (as methods of hormonal contraception and as HRT), thyroxine (as levothyroxine, for hypothyroidism) and steroids (for autoimmune diseases and several respiratory disorders). Insulin is used by many diabetics. Local preparations for use in otolaryngology often contain pharmacologic equivalents of adrenaline, while steroid and vitamin D creams are used extensively in dermatological practice. A "pharmacologic dose" of a hormone is a medical usage referring to an amount of a hormone far greater than naturally occurs in a healthy body. The effects of pharmacologic doses of hormones may be different from responses to naturally occurring amounts and may be therapeutically useful. An example is the ability of pharmacologic doses of glucocorticoid to suppress inflammation. Test no. 1 Define hormone and what is the effect of hormones 86 Unit thirty 1-30 regulation of body temperature The temperature of the body is regulated by neural feedback mechanisms which operate primarily through the hypothalmus. The hypothalmus contains not only the control mechanisms, but also the key temperature sensors. Under control of these mechanisms, sweating begins almost precisely at a skin temperature of 37°C and increases rapidly as the skin temperature rises above this value. The heat production of the body under these conditions remains almost constant as the skin temperature rises. If the skin temperature drops below 37°C a variety of responses are initiated to conserve the heat in the body and to increase heat production. These include Vasoconstriction to decrease the flow of heat to the skin. Cessation of sweating. Shivering to increase heat production in the muscles. Secretion of norepinephrine, epinephrine, and thyroxine to increase heat production 2-30 body temperature Body temperature is a measure of the body's ability to generate and get rid of heat. The body is very good at keeping its temperature within a narrow, safe range in spite of large variations in temperatures outside the body. When you are too hot, the blood vessels in your skin expand (dilate) to carry the excess heat to your skin's surface. You may begin to sweat, and as the sweat evaporates, it helps cool your body. When you are too cold, your blood vessels narrow (contract) so that blood flow to your skin is reduced to conserve body heat. You may start shivering, which is an involuntary, rapid contraction of the muscles. This extra muscle activity helps generate more heat. Under normal conditions, this keeps your body temperature within a narrow, safe range. 3-30 Where is body temperature measured? Your body temperature can be measured in many locations on your body. The mouth, ear, t, and rectum are the most commonly used places. Temperature can also be measured on your forehead. What are Fahrenheit and Celsius? Thermometers are calibrated in either degrees Fahrenheit (°F) or degrees Celsius (°C), depending on the custom of the region. Temperatures in the United States are often measured in degrees Fahrenheit, but the standard in most other countries is degrees Celsius. 87 4-30 What is normal body temperature? Most people think of a "normal" body temperature as an oral temperature of 98.6For 37.2 C . This is an average of normal body temperatures. Your temperature may actually be 1°F (0.6°C) or more above or below 98.6F. Also, your normal body temperature changes by as much as 1°F (0.6°C) throughout the day, depending on how active you are and the time of day. Body temperature is very sensitive to hormone levels and may be higher or lower when a woman is ovulating or having her menstrual period. A rectal or ear (tympanic membrane) temperature reading is 0.5 to 1°F (0.3 to 0.6°C) higher than an oral temperature reading. A temperature taken in the armpit is 0.5 to 1°F (0.3 to 0.6°C) lower than an oral temperature reading. 5-30 What is a fever? In most adults, an oral temperature above 100F or a rectal or ear temperature above 101F is considered a fever. A child has a fever when his or her rectal temperature is 100.4F or higher. What can cause a fever? A fever may occur as a reaction to: Infection. This is the most common cause of a fever. Infections may affect the whole body or a specific body part (localized infection). Medicines, such as antibiotics, narcotics, barbiturates, antihistamines, and many others. These are called drug fevers. Some medicines, such as antibiotics, raise the body temperature directly; others interfere with the body's ability to readjust its temperature when other factors cause the temperature to rise. Severe trauma or injury, such as a heart attack, stroke, heat exhaustion or heatstroke, or burns. Other medical conditions, such as arthritis, hyperthyroidism, and even some cancers, such as leukemia, Hodgkin's lymphoma, and liver and lung cancer. Test no.1 What is the normal rate of temperature in human Test no. 2 Define fever and cause of it 88 References: 1- Elatine N.Marteb,R.N. (2006) . Essentials of Human Anatomy and Physiology( eight edition). 2- Memmler,Ruth Lundeen . (1990). structure and function of the human body ( fourth edition ) 3- Gerard j.Tortora , Nichdas p. Anagnostakos . (1987). Principles of anatomy and physiology ( fifth edition ) 89 Ministry of higher education and scientific research Foundation of technical education Learning package in filed Medical physiology ( practical part ) Presented to the first class students Of Institute of medical technology – Baghdad Department of community health Designed by Dr. rawaa adnan faraj 2009 -2010 90 A: Over view 1- Target population : This learning package had been designed to the first class students in the Community Health Dept. of the Institute of Medical Technology –Baghdad. The students are able to do some clinical and hematological test for human body 91 Unit one The microscope Parts and Specifications Historians credit the invention of the compound microscope to the Dutch spectacle maker, Zacharias Janssen, around the year 1590. The compound microscope uses lenses and light to enlarge the image and is also called an optical or light microscope (vs./ an electron microscope). The simplest optical microscope is the magnifying glass and is good to about ten times (10X) magnification. The compound microscope has two systems of lenses for greater magnification. 92 1. the ocular, or eyepiece lens that one looks into 2. the objective lens, or the lens closest to the object. Low power 10X high power 40X , oil immersion power 100X Total Magnification power for 10X= 100X Total magnification power of 40X = 400X Total magnification power of 100X = 1000X Before using a microscope, it is important to know the functions of each part. Eyepiece Lens: the lens at the top that you look through. They are usually 10X or 15X power. Tube: Connects the eyepiece to the objective lenses Arm: Supports the tube and connects it to the base Base: The bottom of the microscope, used for support Illuminator: A steady light source (110 volts) used in place of a mirror. If your microscope has a mirror, it is used to reflect light from an external light source up through the bottom of the stage. Stage: The flat platform where you place your slides. Stage clips hold the slides in place. If your microscope has a mechanical stage, you will be able to move the slide around by turning two knobs. One moves it left and right, the other moves it up and down. Revolving Nosepiece or Turret: This is the part that holds two or more objective lenses and can be rotated to easily change power. Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4X, 10X, 40X and 100X powers. When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X , 400X and 1000X. To have good resolution at 1000X, you will need a relatively sophisticated microscope with an Abbe condenser. The shortest lens is the lowest power, the longest one is the lens with the greatest power. Lenses are color coded and if built to DIN standards are interchangeable between microscopes. The high power objective lenses are retractable (i.e. 40XR). This means that if they hit a slide, the end of the lens will push in (spring loaded) thereby protecting the lens and the slide. All quality microscopes have achromatic, parcentered, parfocal lenses. Rack Stop: This is an adjustment that determines how close the objective lens can get to the slide. It is set at the factory and keeps students from cranking the high power objective lens down into the slide and breaking things. You would only need to adjust this if you were using very thin slides and you weren't able to focus on the specimen at high power. (Tip: If you are using thin slides and can't focus, rather than adjust the rack stop, place a clear glass slide under the original slide to raise it a bit higher) Condenser Lens: The purpose of the condenser lens is to focus the light onto the specimen. Condenser lenses are most useful at the highest powers (400X and above). Microscopes with in stage condenser lenses render a sharper image than those with no lens (at 400X). If your microscope has a maximum power of 400X, you will get the maximum benefit by using a condenser lenses rated at 0.65 NA or greater. 0.65 NA condenser lenses may be mounted in the stage and work quite well. A big advantage to a stage mounted lens is that there is one less focusing item to deal with. If you go to 1000X then you should have a focusable condenser lens with an N.A. of 1.25 or greater. Most 1000X microscopes use 1.25 Abbe condenser lens systems. The Abbe condenser lens can be moved up and down. It is set very close to the slide at 1000X and moved further away at the lower powers. Diaphragm or Iris: Many microscopes have a rotating disk under the stage. This diaphragm has different sized holes and is used to vary the intensity and size of the cone of light that is 93 projected upward into the slide. There is no set rule regarding which setting to use for a particular power. Rather, the setting is a function of the transparency of the specimen, the degree of contrast you desire and the particular objective lens in use. How to Focus Your Microscope The proper way to focus a microscope is to start with the lowest power objective lens first and while looking from the side, crank the lens down as close to the specimen as possible without touching it. Now, look through the eyepiece lens and focus upward only until the image is sharp. If you can't get it in focus, repeat the process again. Once the image is sharp with the low power lens, you should be able to simply click in the next power lens and do minor adjustments with the focus knob. If your microscope has a fine focus adjustment, turning it a bit should be all that's necessary. Continue with subsequent objective lenses and fine focus each time. 94 Unit two &three Blood smear Blood smear Fig. 1 blood film A blood film or peripheral blood smear is a microscope slide made from a drop of blood, that allows the cells to be examined microscopically. Blood films are usually done to investigate the normal blood cells ( R.B.C, W.B.C, platelets) . Materials 1- Lancet , ethanol 70% , cotton 2- Slides , spreader slide 3- Drop of blood 4- Methanol 5- Leishman stain Preparation Blood films are made by placing a drop of blood on one end of a slide, and using a spreader slide to disperse the blood over the slide's length. The aim is to get a region where the cells are spaced far enough apart to be counted and differentiated. The slide is left to air dry, after which the blood is fixed to the slide by immersing it briefly in methanol. The fixative is essential for good staining and presentation of cellular detail. After fixation, the slide is stained to distinguish the cells from each other. o o o Stain:Giemsa stain Leishman stain 95 Characteristic red blood cell abnormalities are anemia, sickle cell anemia and spherocytosis. White blood cells are classified according to their propensity to stain with particular substances, the shape of the nuclei and the granular inclusions. Types of white blood cells Neutrophil granulocytes usually make up close to 80% of the white count. They have multilobate nuclei and lightly staining granules. They assist in destruction of foreign particles by the immune system by phagocytosis and intracellular killing. Eosinophil granulocytes have granules that stain with eosin and play a role in allergy and parasitic disease. Eos have a multilobate nucleus. Basophil granulocytes are only seen occasionally. They are polymorphonuceated and their granules stain dark with alkaline stains They are further characterised by the fact that the granules seem to overlie the nucleus. Basophils are similar if not identical in cell lineage to mast cells, although no conclusive evidence to this end has been shown. Mast cells are "tissue basophils" and mediate certain immune reactions to allergens. Lymphocytes have very little cytoplasm and a large nucleus (high NC ratio) and are responsible for antigen-specific immune functions, either by antibodies (B cell) or by direct cytotoxicity (T cell). The distinction between B and T cells cannot be made by light microscopy. Plasma cells are mature B lymphocytes that engage in the production of one specific antibody. They are characterised by light basophilic staining and a very eccentric nucleus. 96 Unit four and five Differential Leukocyte Count Differential count is useful to identity changes in the distribution of white cells which may be related to specific types of disorders. Clinical Significance Differential count is useful to identity changes in the distribution of white cells which may be related to specific types of disorders. It also gives idea regarding the severity of the disease and the degree of response of the body. Neutrophilia Increase in the percentage of neutrophils is called neutrophilia. All the physiological causes that produce leukocytosis give rise to neutrophilia.The commonest pathological cause is pyogenic bacterial infection. Decrease in neutrophils (Neutropenia) is ob served in infections such as bacterial (typhoid) viral (measles influenza etc.) and in other conditions such as anemias (aplastic, megaloblastic, iron deficiency) and in suppression of bone marrow by various drugs and radiation. Lymphocytosis It may be relative or absolute. Relative lymphocytosis: In this condition the actual number of lymphocytes is unchanged but due to decrease in neutrophils mainly the differential count shows an increase in lymphocytes. Absolute lymphocytosis It is observed in 1. Children 2. Certain infections such as mumps, cough. measles, influenza, syphilis, tuberculosis, typhoid and other chronic infections 3. Infectious mononucleosis 4. Chronic lymphatic leukemia 5. Lymphopenia It is observed in acute stages of infections and in excess irradiation. Eosinophilia It is observed in asthma, hypersensitivity reactions, parasitic infestations and in chronic inflammatory diseases 97 Monocytosis It is observed in tuberculosis, malaria, subacute bacterial endocarditis typhoid and in Kala azar. Basophilia It is usually observed in chronic myeloid leukemia. Normal values: (Male or Female) Neutrophils : 40-75% (mean: 57%) a) Segmented : 2-6% (mean 3%) b) band forms : 50-70% (mean: 54%) Eosinophils : 1-4% (mean 2%) Basophils : 0-1 % Lymphocytes : 20-45 % (mean: 37%) Monocytes : 2 8% (mean 6%) Specimen The blood smears should be preferably prepared immediately after skin puncture or venipuncture before mixing with anticoagulant. If EDTA blood is used the smears should be prepared within 1 to 2 hours after blood drawing.Other anticoagulants do not give satisfactory results.The blood smears should be immediately fixed in methanol. Requirements 1) Microscope slides and a glass spreader 2) Cedar wood oil (Immersion oil) 3) lancet , cotton ethanol 70%, droop of blood 4) Reagents A. leshiman stain: It is prepared by dissolving 0.15 g of powdered stain in 100 ml of (acetone free) methyl alcohol Store in an amber colored bottle at room temperature (25°C ± 5°C). The stain improves on standing for about a week B. Buffer (pH: 7.0): It is prepared as follows: · Sodium dihydrogen phosphate (NaH2PO4.2H2O) : 3.76 g · Potassium dihydrogen phosphate (KH2PO4) : 2.10 g · Distilled water to 1000 ml. Keep at room temperature (25°C ±5°C). 98 Principle The polychromic staining solutions (Wright, Leishman Giemsa) contain methylene blue and eosin. These basic and acidic dyes induce multiple colors when applied to cells. Methanol acts as fixative and also as a solvent. The fixative does not allow any further change in the cells and makes them adhere to the glass slide. The basic component of white cells (i.e. cytoplasm) is stained by acidic dye and they are described as eosinophilic or acidophilic. The acidic components (e.g. nucleus with nucleic acid) take blue to purple shades by the basic dye and they are called basophilic.The neutral components of the cell are stained by both the dyes. Procedure A thin smear is prepared by spreading a small drop of blood evenly on a slide. Making the film 1. Take a clean dry (grease free) slide 2. Transfer a small drop of blood near the edge of the slide. 3. Place the spreader slide at an angle of 30°. Pull back the spreader until it touches the drop of blood. Let the blood run along the edge of the spreader 4. Push the spreader forward to the end of the slide with a smooth movement. 5. Dry the blood smear at room temperature. Adequate drying is essential to pre serve the quality of the film. Precautions 1. Dirty slides do not give an even smear 2. Use an appropriate size of blood drop 3. After putting the drop on the slide, make the smear immediately for even distribution of white blood cells on the slide. 4. The thickness of the smear depends on the angle of the spreader. If the angle is less than 300 a thinner smear is obtained and if the angle is more than 300 a thicker smear is obtained. 5. The film must be smooth at the end. There should be no lines extending across or down through the film and it should not contain holes. 99 Identification marking By using a lead pencil or a ball pen, write the identification number on the slide. Fixing the Smear The slide should be stained after making the smear. Methanol present in the stain fixes the smear. If the staining is to be done later, the blood smear must be fixed with methanol for 2 to 3 minutes to prevent distortion of cells. Staining the Film 1. Cover the smear with the staining solution by adding 10-15 drops on the smear. Wait exactly for one minute. 2. Add equal number of the drops of buffer solution. Mix the reaction mixture adequately by blowing on it through a pipette. Wait for 10 minutes. 3. Wash the smear by using tap water (tap water is preferred because sometimes if distilled water is not stored properly it becomes slightly acidic and gives unsatisfactory results). 4. Stand the slide in a draining rack or on the laboratory counter to dry. Precautions 1. Avoid formation of deposits of stain. They appear on the film as masses of little black spots. In that case rinse the slide twice with methanol. Dry and restain using filtered stain 2. Poor staining makes the film blue pink or too dark 3. Use neutral water Acidic water produces red staining effects and alkaline one gives blue effects. If the film is too blue, rinse it twice in 1% boric acid in 95% ethanol and examine under the micro scope after drying. Examination of Film 1. First examine the stained smear under the low power. In an ideal smear three zones will appear (i) Thick area (head) (ii) body and (iii) thin end of the smear (tail). 2. Choose the portion slightly before, the tail—end where the red cells are, beginning to overlap. 3. Place a drop of immersion oil on the smear. Switch to the oil immersion objective and increase the light by opening the iris diaphragm. 4. Examine the film by moving from one field to the next systematically. Record the type of leukocytes seen in each field. 100 5. Count at least a total of 100 leukocytes. Counting 500 leukocytes gives high degree of accuracy. Additional Information Following staining solutions are also used for the staining of blood films: Giemsa stain a) 0.3 g of Giemsa staining powder is dissolved in glycerol and kept at 56-60°C (in a water bath) for 2 hours. b) 25 ml of acetone free methyl alcohol is added and the prepared staining solution is kept at room temperature for one week. c) After filtering it is stored in an amber colored bottle at room temperature. d) Before use it is necessary to dilute this staining solution 1:10 in the buffer solution of pH 7.0. 101 Unit sex , seven and eight Blood Cell Counts : Red blood cell ,white blood cells , platelets The cells most often counted by this technique are red cells, white cells, platelets. Introduction The technique of counting of the blood cells is known as hemocytometry. This involves manual counting of the cells with the help of a microscope after diluting blood in respective diluting fluids. The cells most often counted by this technique are red cells, white cells, platelets. The hemocytometer technique, however, can not differentiate the various types of the individual cells. Requirements 1) Microscope , blood , cotton, lancet , ethanol % 2) RBC Pipette This pipette has a large bulb, which contains a red glass bead. It has three marks 0.5, 1.0 and 101. Blood is drawn to 0.5 mark and then diluting fluid is drawn up to the mark 101. The dilution of blood is 1:200. 3) WBC Pipette It is smaller than the red cell pipette and its bulb contains a white glass bead. It has three marks 0.5, 1.0 and 11. The blood is drawn up to 0.5 mark and then diluting fluid is drawn up to 11 mark. The dilution of blood is 1: 20. 102 4) The Counting Chamber The chamber most commonly used is the improved Neubauer chamber which has an area of 9 sq. mm and a depth of 0.1 mm. The two stages are separated from two ridges, one on either side, by a gutter. The surface of the two ridges is 1/10 mm above the stage. The 9 sq. mm area of the counting chamber is divided into 9 squares. The four corner squares measure 1 sq. mm area. The squares at the corner are divided into 16 small squares each and are used for counting white cells. The central square is divided into 25 squares and each of these square is further divided into 16 small squares, each square measures 1/400 sq. mm in area. Five of the medium squares (or 80 small squares) are used in counting red cells. 5) Cover Slips A special type of cover slip is used with a very smooth and even surface. These are available in two sizes (a) 16 x 22 mm and (b) 22 x 23 mm. The thickness of the cover slips may be 0.3 mm, 0.4 mm or 0.5 mm. Note: Following precautions are taken while using the counting chamber and the pipettes: 1. The counting chamber should be clean and dry. 2. After pipetting blood up to the mark, wipe the out side of the pipette by using cotton or gauze. 3. Diluting fluid is drawn up to the mark and care is taken not to allow air bubbles to enter. 4. The pipette is rotated rapidly between the fingers to allow the fluid to mix well. The fluid should not be allowed to run out of the pipette. This is possible if the pipette is kept perfectly horizontal during mixing. 5. Initial few drops should be discarded from the pipette. 6. The filling of the chamber should be done in one application of the tip of the pipette. Fluid should not flow in to the surrounding moat. The fluid charged chamber should be placed on a film platform (or bench), away from direct sun light or other source of heat. The cover glass should be of a special thick glass and it should be perfectly flat. 7. Air bubbles should not be present under the cover slip. 8. The diluting fluid should not overrun the cover slip. 9. The cells are allowed to settle for 2 to 3 minutes so that they are seen in the same plane of focus. 10. Longer waiting leads to drying of the fluid and disturbs the cells. 103 11. Before the counting the condenser and mirror of the microscope should be properly adjusted. 12. The distribution of the cells should be observed carefully. If it is not proper the preparation should be discarded and the blood cell dilution procedure should be repeated. 13. First the low power is used to focus the ruling on the chamber. The counting is done under the high dry power (40 X objective). 14. While counting, the cells contained within the square and those cells touching or lying on the lines of any two adjacent sides (top and right, or bottom and left) are included in the count. 15. The error of pipettes and dilution can be decreased by using larger volumes of blood and diluting fluid. Note: The preparation must be discarded and the filling procedure should be repeated by using another clean and dry chamber if1. Chamber area is incompletely filled 2. Fluid overflows into moat 3. Air bubbles are seen anywhere in chamber area Normal value of white blood cells 1. 2. 3. 4. 5. Age 6 Months to 2 years: 6.0 to 17.5 (Mean 11.0) Age 4 Years: 5.5 to 15.5 (Mean 9.1) Age 6 Years: 5.0 to 14.5 (Mean 8.5) Age 8 to 16 Years: 4.5 to 13.5 (Mean 8.1) Age over 21 Years: 4.5 to 11.0 (Mean 7.4) Normal value of red blood cells 2. Findings: Normal Values (in 10^6/ul or 10^12/L) per age 1. Age <1 month: 3.6 to 6.6 2. Age 1-6 months: 2.7 to 5.4 3. Age 0.5 - 6 years: 3.7 to 5.3 4. Age 6-12 years: 4.0 to 5.2 5. Female 1. Age 12-18 years: 4.1 to 5.1 2. Age >18 years: 3.8 to 5.2 6. Male 1. Age 12-18 years: 4.5 to 5.3 2. Age >18 years: 4.4 to 5.9 104 105 Unit nine and ten Determination of Hemoglobin. Clinical Significance A decrease in hemoglobin below normal range is an indication of anemia. An increase in hemoglobin concentration occurs in hemoconcentration due to loss of body fluid in severe diarrhea and vomiting. High values are also observed in congenital heart disease (due to reduced oxygen supply in emphysema and also in polycythemia. Hemoglobin concentration drops during pregnancy due to hemodilution. Normal values Men Women Children(up to 1 year) Children (10-12 years) Infants (full term cord blood) Hb, g/dl 13-18 12-16.5 11.0-13.0 11.5-14.5 13.5-19.5 Method Sahli (acid hematin) method Principle When blood is added to 0.1 N hydrochloric acid, hemoglobin is converted to brown colored acid hematin. The resulting color after dilution is coin- pared with standard brown glass reference blocks of a Sahli hemoglobinometer Specimen Capillary blood or thoroughly mixed anticoagulated (EDTA or double oxalated) venous blood. The specimen need not be a fasting sample. Requirements 1) Sahli hemoglobinometer: It consists of a. A standard brown glass mounted on a comparator b. A graduated tube c. Hb-pipette (0.02 ml) Refer to the colored plates. Note: The graduations on currently used Hellige tube gives 14.5 g as 100%. These are square tubes with graduations in percent on one side and grams per 100 ml (dl) on the other side. 106 2) 0. IN hydrochloric acid 3) Distilled water 4) Pasteur pipettes 5) lancet ,ethanol 70%,cotton ,blood Procedure 1. By using a Pasteur pipette add 0.1 N hydrochloric acid in the tube up to the lowest mark (20%mark). 2. Draw blood up to 20 µl mark in the Hb-pipette. Adjust the blood column, carefully without bubbles. Wipe excess of the blood on the sides of the pipette by using a dry piece of cotton. 3. Transfer blood to the acid in the graduated tube rinse the pipette well mix the reaction mixture and allow the tube to stand for at least 10 minutes 4. Dilute the solution with distilled water by adding few drops at a time carefully and by mixing the reaction mixture, until the color matches with the glass plate in the comparator 5. The matching should be done only against natural light. The level of the fluid is noted at its lower meniscus and the reading corresponding to this level on the scale is recorded in g/dl. Additional Information 1. Methemoglobin carboxyhemoglobin and sulfhemoglobin are not converted to acid hematin by 0.1 N hydrochloric acid. 2. This method is useful for places where a photometer is not available. 3. It can give an error up to 1 g/dl Precaution 1. Immediately after use rinse the Hb pipette by using tap water in a beaker. This prevents blocking of the pipette. 107 Unit eleven and twelve Determination of PCV by Micro Hematocrit Method Determination of PCV by Micro Hematocrit Method In the case of difficulty in drawing sufficient amount of blood, microhematocrit method is used. It is useful particularly in pediatric patients. The method is ideal for skin puncture. Specimens 1. EDTA or oxalated specimen (use plain capillary tubes). Or 2. Capillary blood (use heparinized capillaries). Note: It is necessary to determine PCV within 6 hours - after the blood collection. Principle Blood is centrifuged in a sealed capillary tube and PCV is determined by a special hematocrit reader. Requirements 1) Hematocrit centrifuge It runs at high speed and produces RCF of 12,000 x g and runs at a speed of about 15,000 RPM. It contains a head to hold the capillary tubes. 2) Hematocrit reader This is supplied by the manufacturer. 3) Capillary hematocrit tubes These are 75 mm in length with approximately 1 mm diameter. 4) Soft wax or modelling clay This is used to seal the end of the hematocrit tube 5) lancet , ethanol 70% ,cotton , blood Procedure 1. Draw the blood into an appropriate capillary tube. Fill in the tube to about ¾ length 2. Seal both the ends of the tube with soft wax or modelling clay. It is plugged to a depth of about 1 centimeter 3. Write identification number on the tube by using a marking pencil. 4. Place the tube with another similar tube in the radial grooves of the centrifuge head exactly opposite to each other (empty capillary tube also can be used). 5. Close the centrifuge cover and centrifuge the tubes at high speed (about 15,000 RPM) for 5 minutes. 108 6. Remove the capillary tube. It will show three layers — (a) Clear plasma at the top, (b) Whitish buffy coat at the middle and (c) column of red cells at the bottom. 7. Hold the tube against the hematocrit scale so that the bottom of the column of red cells is aligned with the horizontal zero line (exclude the height of clay). 8. Move the tube across the scale until the line marked 1.0 passes through the top of the plasma column. 9. The line that passes through the top or the column of red cells gives the value of PCV (hematocrit). 10. Source of Error 1. Hemolyzed specimen will yield false low values. 2. Inadequate mixing of blood and incompleteness of packing may lead to erroneous results. 3. Disadvantages It requires a special centrifuge and disposable capillary tubes. Additional observations Note any abnormal findings such as 1) the color of plasma (yellow for jaundice and reddish for hemolysis) 2) Increased huffy coat for increased white blood cells. 109 P.C.V method 110 Unit thirteen and fourteen Erythrocyte Sedimentation Rate (ESR) The rate at which the red cells fall is known as the erythrocyte sedimentation rate. (1) ESR is greater in women than in men and it is related to the difference in PCV. (2) During pregnancy ESR gradually increases after 3rd month and returns to normal in about 3 to 4 weeks after delivery. (3) ESR is low in infants and gradually increases up to puberty. It decreases until old age and it again increases. (4) The Laboratory factors which influence ESR are as follows: a) Time: The test should be performed as early as possible after the collection of fasting specimen. There is progressive decrease in sedimentation in first four hours and after that there is a rapid decrease in sedimentation. b) The length of the ESR tube: ESR is greater with longer tubes (Westergren’s tube) than with shorter tube (Wintrobe’s tube). To ensure reliable results the column of blood should be as high as possible. The internal diameter of the tube should be more than 2.5 mm. The tubes should be kept in vertical position. Deviation of the tubes from the vertical position increases the ESR. c) Temperature: The red cell sedimentation is increased at higher temperature. Clinical Significance 1. ESR is increased in all conditions where there is tissue breakdown or where there is entry of foreign proteins in the blood, except for localized mild infections. The determination is useful to check the progress of the disease. If the patient is improving the ESR tends to fall. If the patient’s condition is getting worse the ESR tends to rise. The changes of ESR are, however, not diagnostic of any specific disease. 111 Determination of Erythrocyte Sedimentation Rate Method Westergren’s method. The following figure is the Determination of ESR by Westergren’s Method Normal range Male 0-15 mm after 1st hour Female 0-20 mm after 1st hour Specimens 1. Small tube (100 * 10 mm) with 2.5 ml mark is used for blood collection. (If the tube is not graduated, pipette out 2.5 ml of 3.8% sodium citrate in the tube and after marking the level of fluid, remove 2.0 ml of the solution leaving 0.5 ml of the anticoagulant in the tube). 2. The tubes with 0.5 ml of 3.8% odium citrate should be kept ready before blood collection. 3. Patient should be fasting for 12 to 16 hours. Collect blood by venipuncture and add in the tube up to the mark and mix carefully. Note: Fasting EDTA blood also can be used. In that case add 2.0 ml of blood to 0.5 ml, 3.8% sodium citrate. 112 Requirement 1. 2. 3. 4. Westergren’s ESR lube Stand for holding the tube Timer or watch lancet ,cotton, ethanol 70%, blood Procedure 1. Fill the Westergren’s tube exactly up to zero mark by means of a rubber bulb (avoid air bubbles). 2. Place the tube upright in the stand. It should fit evenly into the groove of the stand. 3. Note the time. Allow the tube to stand for exactly one hour. 4. Exactly after one hour, note the level to which the red cell column has fallen. 5. Report the result in terms of mm/after 1st hour. Precaution Wash the tubes as early as possible, under running tap water. Rinse in deionized water and dry in the incubator between 40oC-50oC. 113 Unit fifteen and sixteen Blood groups test Requirement Lancets Plastic pipette Alcohol swab Blood Blood group test ( anti A, anti B , anti D ) Precautions Perform test at room temperature 1. Wash your hands before carrying out the test and again after carrying out the test. 2. Wipe a fingertip with the alcohol impregnated tissue provided and allow it to dry. 3. Place the lancet against the end of the finger and press the green body against your finger to release the needle. 4. Massage the finger from the bottom to the top to encourage bloodflow. Press the blood towards fingertip. Repeat pressing until a drop with a 3 to 4 mm (1/8 inch) diameter is seen. 114 5. Transfer the blood to an glass slide, approached from beneath the finger. Don’t smear the blood over the skin. 6. Place the anti A with the drop of blood into the first circle. and blood mixture until the coloured dry material has dissolved. 7. Repeat this procedure for the other 3 circles, making sure you use a new stick for each circle. 8. As soon as you have finished tilting read and record the results immediately. See the table below for how the results are interpreted. 115 Unit seventeen and eighteen Blood pressure A sphygmomanometer, a device used for measuring arterial pressure. Blood pressure (BP) is the pressure (force per unit area) exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through arteries and capillaries, and toward the heart through veins. When unqualified, the term blood pressure usually refers to brachial arterial pressure: that is, in the major blood vessel of the upper left or right arm that takes blood away from the heart. Blood pressure may, however, sometimes be measured at other sites in the body, for instance at the ankle. The ratio of the blood pressure measured in the main artery at the ankle to the brachial blood pressure gives the Ankle Brachial Pressure Index (ABPI). Measurement Arterial pressure is most commonly measured via a sphygmomanometer, which historically used the height of a column of mercury to reflect the circulating pressure. Today blood pressure values are still reported in millimetres of mercury (mmHg), though aneroid and electronic devices do not use mercury. For each heartbeat, blood pressure varies between systolic and diastolic pressures. Systolic pressure is peak pressure in the arteries, which occurs near the beginning of the cardiac cycle when the ventricles are contracting. Diastolic pressure is minimum pressure in the arteries, which occurs near the end of the cardiac cycle when the ventricles are filled with blood. An example of normal measured values for a resting, healthy adult human is 115 mmHg systolic and 75 mmHg diastolic (written as 115/75 mmHg, and spoken (in the US) as "one fifteen over seventy-five"). Pulse pressure is the difference between systolic and diastolic pressures. 116 Systolic and diastolic arterial blood pressures are not static but undergo natural variations from one heartbeat to another and throughout the day (in a circadian rhythm). They also change in response to stress, nutritional factors, drugs, disease, exercise, and momentarily from standing up. Sometimes the variations are large. Hypertension refers to arterial pressure being abnormally high, as opposed to hypotension, when it is abnormally low. Along with body temperature, blood pressure measurements are the most commonly measured physiological parameters. Arterial pressures can be measured invasively (by penetrating the skin and measuring inside the blood vessels) or non-invasively. The former is usually restricted to a hospital setting. Units The predominantly used unit for blood pressure measurement is mmHg (millimeter of mercury). For example, normal pressure can be stated as 120 over 80. Palpation methods A minimum systolic value can be roughly estimated without any equipment by palpation, most often used in emergency situations. Palpation of a radial pulse indicates a minimum blood pressure of 80 mmHg, a femoral pulse indicates at least 70 mmHg, and a carotid pulse indicates a minimum of 60 mmHg. However, one study indicated that this method was not accurate enough and often overestimated patients' systolic blood pressure.[1] A more accurate value of systolic blood pressure can be obtained with a sphygmomanometer and palpating for when a radial pulse returns.[2] The diastolic blood pressure can not be estimated by this method.[3] Auscultatory methods Auscultatory method aneroid sphygmomanometer with stethoscope 117 Mercury manometer The auscultatory method uses a stethoscope and a sphygmomanometer. This comprises an inflatable (Riva-Rocci) cuff placed around the upper arm at roughly the same vertical height as the heart, attached to a mercury or aneroid manometer. The mercury manometer, considered to be the gold standard for arterial pressure measurement[citation needed], measures the height of a column of mercury, giving an absolute result without need for calibration, and consequently not subject to the errors and drift of calibration which affect other methods. The use of mercury manometers is often required in clinical trials and for the clinical measurement of hypertension in high risk patients, such as pregnant women. A cuff of appropriate size is fitted smoothly and snugly,then inflated manually by repeatedly squeezing a rubber bulb until the artery is completely occluded. Listening with the stethoscope to the brachial artery at the elbow, the examiner slowly releases the pressure in the cuff. When blood just starts to flow in the artery, the turbulent flow creates a "whooshing" or pounding (first Korotkoff sound). The pressure at which this sound is first heard is the systolic blood pressure. The cuff pressure is further released until no sound can be heard (fifth Korotkoff sound), at the diastolic arterial pressure. Sometimes, the pressure is palpated (felt by hand) to get an estimate before auscultation. 118 Classification The following classification of blood pressure applies to adults aged 18 and older. It is based on the average of seated blood pressure readings that were properly measured during 2 or more office visits. Classification of blood pressure for adults Category systolic, mmHg Hypotension < 90 or < 60 Normal 90 – 119 and 60 – 79 Prehypertension 120 – 139 or 80 – 89 Stage 1 Hypertension 140 – 159 or 90 – 99 Stage 2 Hypertension ≥ 160 or ≥ 100 119 diastolic, mmHg Unit nineteen and twenty Temperature measurement A medical/clinical thermometer showing the temperature of 38.7 °C Temperature measurement using modern scientific thermometers and temperature scales goes back at least as far as the early 18th century, when Gabriel Fahrenheit adapted a thermometer (switching to mercury) and a scale both developed by Ole Christensen Røemer. Fahrenheit's scale is still in use, alongside the Celsius scale and the Kelvin scale. A medical/clinical thermometer showing the temperature of 38.7 °C Medical thermometers are used for measuring human body temperature, with the tip of the thermometer being inserted either into the mouth (oral temperature), under the armpit (axillary temperature), or into the rectum via the anus (rectal temperature). Classification, by technology Electronic clinical thermometers The traditional mercury-filled medical thermometer works in the same way as a meteorological maximum thermometer. The thermometer consists of a mercury-filled bulb attached to a small tube. There is a constriction in the neck close to the bulb. As the temperature rises, the force of the expansion pushes the mercury up the tube through the constriction. When the temperature falls, the column of mercury breaks at the constriction and cannot return to the bulb, thus remaining stationary in the tube. To reset the thermometer, it must be swung sharply. 120 When it is designed for use in humans, the typical range of this kind of thermometer is from about 35°C to 42°C or 89.6°F to 109.4°F. The temperature is obtained by reading the scale inscribed on the side of the thermometer. Close-up of a maximum thermometer. The break in the column of mercury is visible. In the 1990s, mercury-based thermometers were found too risky to handle; the vigorous swinging needed to "reset" a mercury maximum thermometer makes it easy to accidentally break it, and spill the poisonous mercury. Mercury thermometers have largely been replaced with electronic digital thermometers, or, more rarely, thermometers based on liquids other than mercury (such as heat-sensitive liquid crystals). Other modern options include digital Infrared contact or noncontact thermometers, which are also called scanner thermometers. Most medical thermometers may be used to take oral, axillary, vaginal, or rectal temperatures. To eliminate the risk of patient cross-infection, disposable single-use clinical thermometers and probe covers are employed in clinics and hospitals. Classification, by location Oral Oral temperature may only be taken from a patient who is capable of holding the thermometer in their mouth correctly and securely, which generally excludes small children or people who are overcome by coughing, weakness, or vomiting. (This is less of a problem with fastreacting digital thermometers, but was certainly an issue with mercury thermometers, which took several minutes to register a temperature.) Another counter-indication is if the patient has drunk a hot or cold liquid beforehand, in which case one has to wait or use another method. 121 Rectal Rectal thermometry Rectal temperature-taking, especially if performed by a person other than the patient, should be facilitated with the use of lubricant (such as petroleum jelly (now discouraged) or a water-based personal lubricant). Although rectal temperature is the most accurate, this method may be considered embarrassing in some countries or cultures, especially if used on patients older than young children; also, if not taken the correct way, a rectal temperature-taking can be uncomfortable and in some cases painful for the patient. Rectal temperature-taking is considered the method of choice for infants for the general public and the rectal route is also desirable in infants from a nursing point of view.[3] 122 Unit twenty one and twenty two Electro cardio graphic (E.C.G) Electrocardiography is a commonly used, noninvasive procedure for recording electrical changes in the heart. The record, which is called an electrocardiogram (ECG or EKG), shows the series of waves that relate to the electrical impulses that occur during each beat of the heart. The results are printed on paper and/or displayed on a monitor to provide a visual representation of heart function. The waves in a normal record are named P, Q, R, S, and T, and follow in alphabetical order. The number of waves may vary, and other waves may be present. Purpose Electrocardiography is a starting point for detecting many cardiac problems, including angina pectoris, stable angina, ischemic heart disease, arrhythmias (irregular heartbeat), tachycardia (fast heartbeat), bradycardia (slow heartbeat), myocardial infarction (heart attack), and certain congenital heart conditions. It is used routinely in physical examinations and for monitoring a patient's condition during and after surgery, as well as in the intensive care setting. It is the basic measurement used in exercise tolerance tests (i.e., stress tests) and is also used to evaluate symptoms such as chest pain, shortness of breath, and palpitations. Description The patient disrobes from the waist up, and electrodes (tiny wires in adhesive pads) are applied to specific sites on the arms, legs, and chest. When attached, these electrodes are called leads; three to 12 leads may be employed for the procedure. Muscle movement may interfere with the recording, which lasts for several beats of the heart. In cases where rhythm disturbances are suspected to be infrequent, the patient may wear a small Holter monitor in order to record continuously over a 24-hour period. This is known as ambulatory monitoring. 123 Special training is required for interpretation of the electrocardiogram. To summarize in the simplest manner the features used in interpretations, the P wave of the electrocardiogram is associated with the contraction of the atria—the two chambers of the heart that receive blood from the veins. The QRS series of waves, or QRS complex, is associated with ventricular contraction, with the T wave coming after the contraction. The ventricles are the two chambers of the heart that receive blood from the atria and that send the blood into the arteries. Finally, the P-Q or P-R interval gives a value for the time taken for the electrical impulse to travel from the atria to the ventricle (normally less than 0.2 seconds). Diagnosis/Preparation Patients are asked not to eat for several hours before a stress test . Before the leads are attached, the skin is cleaned to obtain good electrical contact at the electrode positions and, occasionally, shaving the chest may be necessary. Heart problems are diagnosed by the pattern of electrical waves produced during the EKG, and an abnormal rhythm can be called dysrhythmia. The cause of dysrhythmia is ectopic beats. Ectopic beats are premature heartbeats that arise from a site other than the sinus node— commonly from the atria, atrioventricular node, or the ventricle. When these dysrhythmias are only occasional, they may produce no symptoms or simply a feeling that the heart is turning over or "flip-flopping." These occasional dysrhythmias are common in healthy people, but they also can be an indication of heart disease. The varied sources of dysrhythmias provide a wide range of alterations in the form of the electrocardiogram. Ectopic beats display an abnormal QRS complex. This can indicate disease associated with insufficient blood supply to the heart muscle (myocardial ischemia). Multiple ectopic sites lead to rapid and uncoordinated contractions of the atria or ventricles. This condition is known as fibrillation. When the atrial impulse fails to reach the ventricle, a condition known as heart block results. Aftercare To avoid skin irritation from the salty gel used to obtain good electrical contact, the skin should be thoroughly cleaned after removal of the electrodes. 124 Risks The EKG is a noninvasive procedure that is virtually risk-free for the patient. There is a slight risk of heart attack for individuals undergoing a stress test EKG, but patients are carefully screened for their suitability for this test before it is prescribed. Risk factors for heart disease include obesity, hypertension (high blood pressure), high triglycerides and total blood cholesterol, low HDL ("good") cholesterol, tobacco smoking, and increased age. People who have diabetes mellitus (either type 1 or type 2) are also at increased risk for cardiovascular disease. Normal results When the heart is operating normally, each part contracts in a specific order. Contraction of the muscle is triggered by an electrical impulse. These electrical impulses travel through specialized cells that form a conduction system. Following this pathway ensures that contractions will occur in a coordinated manner. When the presence of all waves is observed in the electrocardiogram, and these waves follow the order defined alphabetically, the heart is said to show a normal sinus rhythm, and impulses may be assumed to be following the regular conduction pathway. In the normal heart, electrical impulses—at a rate of 60–100 times per minute—originate in the sinus node. The sinus node is located in the first chamber of the heart, known as the right atrium, where blood reenters the heart after circulating through the body. After traveling down to the junction between the upper and lower chambers, the signal stimulates the atrioventricular node. From here, after a delay, it passes by specialized routes through the lower chambers or ventricles. In many disease states, the passage of the electrical impulse can be interrupted in a variety of ways, causing the heart to perform less efficiently. The heart is described as showing arrhythmia or dysrhythmia when time intervals between waves, or the order or the number of waves do not fit the normal pattern described above. Other features that may be altered include the direction of wave deflection and wave widths. 125 Alternatives Electrocardiography is the gold standard for detecting heart conditions involving irregularities in electrical conduction and rhythm. Other tests that may be used in conjunction with an EKG include an echocardiogram (a sonogram of the heart's pumping action) and a stress test—an EKG that is done in conjunction with treadmill or other supervised exercise to observe the heart's function under stress—may also be performed. Beasley, Brenda. Understanding EKGs: A Practical Approach. 2nd ed. Upper Saddle River, NJ: Prentice Hall, 2002. The P wave represents atrial activation; the PR interval is the time from onset of atrial activation to onset of ventricular activation. The QRS complex represents ventricular activation; the QRS duration is the duration of ventricular activation. The ST-T wave represents ventricular repolarization. The QT interval is the duration of ventricular activation and recovery. The U wave probably represents "afterdepolarizations" in the ventricles. 126 127 Unit twenty three and twenty four Physical examination Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient. Together with the medical history, the physical examination aids in determining the correct diagnosis and devising the treatment plan. This data then becomes part of the medical record. Format and interpretation Although providers have varying approaches as to the sequence of body parts, a systematic examination generally starts at the head and finishes at the extremities. After the main organ systems have been investigated by inspection, palpation, percussion and auscultation, A complete physical examination includes evaluation of general patient appearance and specific organ systems. It is recorded in the medical record in a standard layout which facilitates others later reading the notes. In practice the vital signs of temperature examination, pulse and blood pressure are usually measured first. Vital signs Vital signs The primary vital signs are: Temperature recording Blood pressure Pulse Respiratory rate Pain level assessment Basic biometrics Height Height is the anthropometric longitudinal growth of an individual. A statiometer is the device used to measure height although often a height stick is more frequently used for vertical measurement of adults or children older than 2. The patient is asked to stand barefoot. Height 128 declines during the day because of compression of the intervertebral discs. Children under age 2 are measured lying horizontally. Weight Weight is the anthropometric mass of an individual. A scale is used to measure weight. Medical professionals generally prefer to use the SI unit of kilograms, and many medical facilities have ready-reckoner conversion charts available for professionals to use, when patients describe their weight in non-SI units. (In the US, pounds and ounces are common, Body mass index (BMI) or height-weight tables, may be used to compare the relationship between height and weight, and may suggest conditions such as obesity or being overweight or underweight. Structure of the written examination record Organ systems Cardiovascular system o Blood pressure, pulse rate and rhythm. Respiratory system Lungs o 4 parts: observation, auscultation, palpation, percussion Observation involves observing the respiratory rate which should be in a ratio of 1:2 Lung auscultation is listening to the lungs bilaterally at the anterior chest and posterior chest. Wheezing is described as a musical sound on expiration or inspiration. It is the result of narrowed airways. Rhonchi are bubbly sounds similar to blowing bubbles through a straw into a sundae. They are heard on expiration and inspiration. It is the result of viscous fluid in the airways. Crackles or rales are similar to rhonchi except they are only heard during inspiration. It is the result of alveoli popping open from increased air pressure For palpation, place both palms or medial aspects of hands on the posterior lung field. Ask the patient to count 1-10. The point of this part is to feel for vibrations and compare between the right/left lung field. If the pt has a consolidation (maybe caused by pneumonia), the vibration will be louder at that part of the lung. This is because sound travels faster through denser material than air. 129 On percussion, you are testing mainly for pleural effusion or pneumothorax. The sound will be more tympanic if there is a pneumothorax because air will stretch the pleural membranes like a drum. If there is fluid between the pleural membranes, the percussion will be dampened and sound muffled. o If there is pneumonia, palpation may reveal increased vibration and dullness on percussion. If there is pleural effusion, palpation should reveal decreased vibration and there will be 'stony dullness' on percussion. 130 Unit twenty five and twenty sex Heart sounds Heart sounds Front of thorax, showing surface relations of bones, lungs (purple), pleura (blue), and heart (red outline). Heart valves are labeled with "M", "T", "A", and "P". First heart sound: caused by atrioventricular valves - Mitral (M) and Tricuspid (T). Second heart sound caused by semilunar valves -- Aortic (A) and Pulmonary/Pulmonic (P). The heart sounds are the noises (sound) generated by the beating heart and the resultant flow of blood through it. This is also called a heartbeat. In cardiac auscultation, an examiner uses a stethoscope to listen for these sounds, which provide important information about the condition of the heart. In healthy adults, there are two normal heart sounds often described as a lub and a dub (or dup), that occur in sequence with each heart beat. These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the AV valves and semilunar valves respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs, adventitious sounds, and gallop rhythms S3 and S4. 131 Heart murmurs are generated by turbulent flow of blood, which may occur inside or outside the heart. Murmurs may be physiological (benign) or pathological (abnormal). Abnormal murmurs can be caused by stenosis restricting the opening of a heart valve, resulting in turbulence as blood flows through it. Abnormal murmurs may also occur with valvular insufficiency (or regurgitation), which allows backflow of blood when the incompetent valve closes with only partial effectiveness. Different murmurs are audible in different parts of the cardiac cycle, depending on the cause of the murmur. Normal heart sounds Normal heart sounds are associated with heart valves closing, causing changes in blood flow. S1 The first heart tone, or S1, forms the "lubb" of "lubb-dub" or "lubb-dup" and is composed of components M1 and T1. Normally M1 precedes T1 slightly. It is caused by the sudden block of reverse blood flow due to closure of the atrioventricular valves, i.e. mitral and tricuspid, at the beginning of ventricular contraction, or systole. When the ventricles begin to contract, so do the papillary muscles in each ventricle. The papillary muscles are attached to the tricuspid and mitral valves via chordae tendineae, which bring the cusps of the valve closed (chordae tendineae also prevent the valves from blowing into the atria as ventricular pressure rises due to contraction). The closing of the inlet valves prevents regurgitation of blood from the ventricles back into the atria. The S1 sound results from reverberation within the blood associated with the sudden block of flow reversal by the valves.[1] If T1 occurs more than slightly after M1, then the patient likely has a dysfunction of conduction of the right side of the heart such as a Right bundle branch block. S2 The second heart tone, or S2, forms the "dub" of "lubb-dub" or "lubbdup" and is composed of components A2 and P2. Normally A2 precedes P2 especially during inspiration when a split of S2 can be heard. It is caused by the sudden block of reversing blood flow due to closure of the aortic valve and pulmonary valve at the end of ventricular systole, i.e. beginning of ventricular diastole. As the left ventricle empties, its pressure falls below the pressure in the aorta, aortic blood flow quickly reverses back toward the left ventricle, catching the aortic valve leaflets and is stopped by aortic (outlet) valve closure. Similarly, as the pressure in the right ventricle falls below the pressure in the pulmonary artery, the pulmonary (outlet) valve closes. The S2 sound results from reverberation within the blood associated with the sudden block of flow reversal. 132 Unit twenty seven Artificial inspiration Respiratory failure is a critical concern for a first aider. If the person is not breathing, then problems such as bleeding, broken bones, burns, scalds, and shock are secondary issues. Given the amount of time your group will spend in the wilds either hiking or camping, it is reasonable and prudent to expect all members of your Patrol and Troop to be proficient in artificial respiration. There are many different techniques for giving artificial respiration. The most widely taught and accepted technique goes by a variety of names, such as "mouth to mouth", "rescue breathing", and "direct". Using this technique, air is expelled from the rescuers lungs directly into the victim's mouth. Assuming a tight air seal, the air is forced into the victim's lungs, and the rescuer watches to see the victim's chest rise with each breath. This technique is direct, and the effectiveness can be visually measured by the rescuer. If the chest of the victim does not rise, then the mouth and throat should be checked for obstructions before rescue breathing is continued. The head, before being tipped back, showing the tongue obstructing the airway 133 To perform rescue breathing perform the following steps: 1. Check the mouth for obstructions, lift the neck and tilt the head back. 2. Pinch the nostrils and seal the mouth, and exhale directly into the victim's mouth. 3. Release the nostrils and the seal around the mouth. 4. Watch for the victim's chest to rise by itself. 5. Feel for a pulse on the victim's neck. 6. If the victim's chest does not start to rise on its own, repeat this process from number 1, until professional help arrives. Rescue breathing should continue at a normal breathing pace of about 12 times per minute, until the victim is fully able to breath on his or her own. Even if the victim appears able to breath on their own, be sure to keep a close watch since relapses are common. 134 Unit twenty eight Respiratory volume Remember: Capacities are always the summation of volumes. TIDAL VOLUME (TV): Volume inspired or expired with each normal breath. INSPIRATORY RESERVE VOLUME (IRV): Maximum volume that can be inspired over the inspiration of a tidal volume/normal breath. Used during exercise/exertion. EXPIRATRY RESERVE VOLUME (ERV): Maximal volume that can be expired after the expiration of a tidal volume/normal breath. RESIDUAL VOLUME (RV): Volume that remains in the lungs after a maximal expiration. CANNOT be measured by spirometry. INSPIRATORY CAPACITY ( IC): Volume of maximal inspiration: IRV + TV FUNCTIONAL RESIDUAL CAPACITY (FRC): Volume of gas remaining in lung after normal expiration, cannot be measured by spirometry because it includes residual volume: ERV + RV VITAL CAPACITY (VC): Volume of maximal inspiration and expiration: IRV + TV + ERV = IC + ERV 135 TOTAL LUNG CAPACITY (TLC): The volume of the lung after maximal inspiration. The sum of all four lung volumes, cannot be measured by spirometry because it includes residual volume: IRV+ TV + ERV + RV = IC + FRC DEAD SPACE: Volume of the respiratory apparatus that does not participate in gas exchange, approximately 300 ml in normal lungs. --ANATOMIC DEAD SPACE: Volume of the conducting airways, approximately 150 ml --PHYSIOLOGIC DEAD SPACE: The volume of the lung that does not participate in gas exchange. In normal lungs, is equal to the anatomic dead space (150 ml). May be greater in lung disease. FORCED EXPIRATORY VOLUME in 1 SECOND (FEV1): The volume of air that can be expired in 1 second after a maximal inspiration. Is normally 80% of the forced vital capacity, expressed as FEV1/FVC. In restrictive lung disease both FEV1 and FVC decrease , thus the ratio remains greater than or equal to 0.8. In obstructive lung disease, FEV1 is reduced more than the FVC, thus the FEV1/FVC ratio is less than 0.8. 136 Unit twenty nine and thrity Urine examination 1. Sample preparation 1. Obtain fresh urine sample 2. Centrifuge 10-15 ml at 1500 to 3000 rpm for 5 minutes 3. Decant supernatant and resuspend remainder of urine 4. Place 1 drop of urine on slide and apply cover slip 2. Examination 1. Urine Cells 1. Urine White Blood Cells 1. Normal <2/hpf in men and <5/hpf in women 2. Urine Red Blood Cells 1. Normal <3/hpf 2. Dysmorphic RBCs suggest glomerular disease 3. Epithelial cells 1. Transitional epithelial cells are normally present 2. Squamous epithelial cells suggest contamination 3. Renal tubule epithelial cells suggest renal disease Bacteria 4. Five bacteria per hpf represents 100,000 CFU/ml 5. Diagnostic for Urinary Tract Infection 1. Men: Any bacteria 2. Women: 5 or more bacteria per hpf Urine Crystals Types 2. Calcium oxalate crystals (square envelope shape) 3. Triple phosphate crystals (coffin lid shape) 1. Associated with increased Urine pH (alkaline) 2. Associated with Proteus Urinary Tract Infection 4. Uric Acid crystals (diamond shape) 5. Cystine crystals (hexagonal shape) 6. urine casts 137 References 1- Beasley, Brenda. Understanding EKGs: (2002). A Practical Approach. 2nd ed. Upper Saddle River, NJ: Prentice Hall, 2- Memmler,Ruth Lundeen . (1990). structure and function of the human body ( fourth edition ) 3- Mulla Afaf ,Abed ulwahid Ibrahim , Yousife Youbart Practical clinical physiology ( first edition ) ,(1989). 138