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The Human Body By Albert Wu Organ Systems • • • • • Digestive System Circulatory System Respiratory System Excretory System Immune System • • • • • • Skeletal System Endocrine System Sensory System Muscular System Nervous System Reproductive System The Digestive System Functions Provides intake of food for nourishment Breaks down the food into components which can be absorbed and utilized by the body Excretes solid waste The Process of Digestion The digestive tract absorbs food mainly by diffusion or active transport. Large food molecules can’t diffuse and are too large to fit the active transport pumps. Therefore, food molecules have to be broken down and absorbed. The digestive system performs both of these functions. Parts of the Digestive System Mouth Teeth Lip Tongue Salivary Glands Pharynx Esophagus Liver Gallbladder (under liver) Large Intestine Stomach Pancreas (under stomach) Rectum Small Intestine Appendix Anus The Alimentary Canal The alimentary canal consists of the organs that form the main digestive tract. The alimentary canal includes: Mouth, Pharynx, and Esophagus Stomach Small Intestine Large Intestine Rectum and Anus The Mouth, Pharynx, and Esophagus The mouth physically breaks down food (using the teeth) and also begins to chemically digest carbohydrates. The tongue senses different foods. The pharynx connects the mouth to the esophagus, which pushes food into the stomach by means of peristaltic contractions. The food enters the stomach via the esophageal sphincter. The mouth and associated organs. The Stomach The stomach is a muscular pouch that receives chewed food from the esophagus. The stomach secretes hydrochloric acid as well as a number of enzymes which chemically digest proteins in food. The half-digested food is called chyme. Muscular contractions of the stomach wall help mix the digesting food and push it into the small intestine through a valve called the pyloric sphincter. The Small Intestine The final stages of chemical breakdown of food occur in the small intestine, which is a long muscular tube. Most nutrients are absorbed in the small intestine. The small intestine’s great length (5.5-6 meters) and internal folds (villi and microvilli) helps give the maximum surface area for absorption of food. Muscular contractions mix the food and move it down the intestine. Right: the lining of the small intestine, seen through a microscope. Parts of the Small Intestine The small intestine has three main sections. In order from the closest to the stomach, they are the duodenum, the jejunum, and the ileum. The first 25 cm is the duodenum. Pancreatic and liver secretions enter the duodenum. The next 2.5 m is the jejunum. It is relatively thick and exhibits high activity in its vascular wall. The pH of the jejunum and the ileum ranges from 7-9. The final 2-4 m is the ileum. The ileum houses a large population of symbiotic bacteria and has many lymph nodes. The Large Intestine The chyme (now mostly digested) enters the large intestine through the ileocecal sphincter. The large intestine absorbs water and electrolytes from it. Indigestible waste material (feces) is pushed into the rectum. The large intestine is shorter than the small intestine but much wider. Parts of the Large Intestine. The large intestine has five main parts. They occur in this order, beginning with the closest to the small intestine. The cecum is a pouch that hangs below the ileocecal sphincter. It is connected to the appendix, a small, wormlike structure. The ascending colon stretches up from the cecum to the liver. The transverse colon extends across the abdomen. The descending colon drops down to the pelvic girdle. The sigmoid colon is s-shaped and connects to the rectum. The Rectum and Anus The rectum collects feces (indigestible material) and periodically excretes them (defecation). The anus is a muscular ring that acts as a valve for the rectum. Accessory Organs The accessory organs secrete substances into the alimentary canal which assist the process of digestion. They are not actually part of the alimentary canal. The accessory organs include: Salivary Glands Pancreas Liver and Gallbladder The Salivary Glands The salivary glands produce saliva, which contains enzymes that break down carbohydrates and kill certain pathogens. Saliva also contains bicarbonate ions which buffer the saliva to prevent enzyme denaturation. The Pancreas The pancreas produces “pancreatic juice”, which is secreted into the small intestine. Pancreatic juice contains a variety of enzymes, including those listed below. Amylase: digests starch Lipase: digests lipids Trypsin: digests proteins Nuclease: digests nucleic acids The pancreas. Pancreatic juice also contains bicarbonate ions, which make an optimum environment for pancreatic enzymes and help neutralize stomach acid. The pancreas is also part of the endocrine system. The Liver and Gallbladder The liver and gallbladder help digest lipids. The liver secretes a liquid called bile, which contains pigments, salts, and cholesterol. The gallbladder collects bile, concentrates it, and secretes it into the small intestine. Bile salts cause lipids to form globules (emulsification) and aid enzymes in digesting the lipids. Enzymes Enzymes are proteins which act as catalysts. They are important in breaking down large food molecules. Different parts of the digestive system produce different enzymes. Digestion of different types of food molecules takes place in different locations. Digestion of Molecules Molecule Location of Digestion Mouth Carbohydrates Small Intestine Stomach Proteins Small Intestine Digestive Enzyme Salivary Amylase Salivary Glands Sucrase, Maltase, Lactase Small Intestine Pancreatic Amylase Pancreas Pepsin Stomach Peptidase Small Intestine Trypsin, Chymotrypsin Carboxypeptidase Stomach Lipids Nucleic Acids Small Intestine Small Intestine Enzyme Producer Pancreas Gastric Lipase Stomach Intestinal Lipase Small Intestine Pancreatic Lipase Pancreas Nuclease Pancreas Physical and Chemical Digestion Physical Digestion Chemical Digestion The physical breakdown of The chemical breakdown pieces of food Increases surface area of food for chemical digestion to be effective of food molecules Breaks large molecules into smaller molecules which can be absorbed Happens at a molecular level Diseases of the Digestive System Pinworms Caused by a small parasitic worm, Enterobius vermicularis. Symptoms: itching in the crotch area, may cause weight loss/anemia. Nearly 1/3 of the world’s population is infected with pinworms, but symptoms are usually mild. Treated with repeated doses of medication to ensure the death of all the pinworm eggs. Diseases (continued) Colorectal Cancer Caused by uncontrolled mitosis of cells in the large intestine Symptoms include abdominal pain, bloody stools or diarrhea, or changes in bowel movements. 4th most common cancer in world, more common in older people or alcoholics, 20% have family history Treated with radiation or chemotherapy Sources Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGraw-Hill: 2007. http://www.google.com/ http://en.wikipedia.org/ http://www.ncbi.nlm.nih.gov/ http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/ The Circulatory System Functions • To move blood around the body, ensuring that all tissues get an adequate supply of nutrients and oxygen. Wastes and carbon dioxide are removed. • To circulate white blood cells for defense against infection and to circulate platelets for damage repair. The Heart • The heart is a muscular pump that contracts forcefully to pump blood through the blood vessels. • The heart has four chambers to pump blood in two circuits: the pulmonary circuit (to the lungs) and the systemic circuit (to the body). • The heart’s rate of contraction can change to suit the body’s oxygen or nutrition needs (example: heart rate increases during exercise). The Heart Aorta Superior Vena Cava Left Pulmonary Artery Right Pulmonary Artery Left Pulmonary Veins Right Pulmonary Veins Left Atrium Right Atrium Pulmonary Trunk Coronary Vessels Mitral Valve Aortic Valve Tricuspid Valve Pulmonary Valve Right Ventricle Papillary Muscles Inferior Vena Cava Left Ventricle Chordae Tendineae Interventricular Septum How the Heart Works • 1. Deoxygenated (oxygen poor) blood arrives at the right atrium through the venae cavae, the right atrium contracts, the blood moves to right ventricle through tricuspid valve, the tricuspid valve closes. • 2. The right ventricle contracts, pumping blood through the pulmonary valve and pulmonary artery to lungs where the blood picks up oxygen, the pulmonary valve closes. • 3. Oxygenated blood arrives at left atrium via pulmonary veins, left atrium contracts, the blood moves to left ventricle through mitral valve, the mitral valve closes. See the heart diagram on slide 25. How the Heart Works • 4. Left ventricle contracts, pumping oxygenated blood through the aortic valve and aorta into the body, where the blood gives up its oxygen. The cycle starts again. • The tricuspid and mitral valves are operated by the chordae tendineae and the papillary muscles. The pulmonary and aortic valves are semilunar valves, which are closed by blood pressure. Blood Vessels • There are several types of blood vessels. • Arteries and arterioles: carry blood away from the heart. • Capillaries: allow exchange of oxygen and nutrients between blood and tissues. • Veins and venules: carry blood back to the heart. Here is a cross section of an artery (right) and a vein (left). Notice the difference in thickness of the walls of the vessels. Arteries and Arterioles • Arteries and arterioles carry blood away from the heart. Arterioles are small arteries. • Blood pumped from the heart is under high pressure, so arteries and arterioles have a very thick and muscular wall to deal with the pressure. A cross section of an artery. Veins and Venules • Veins and venules carry blood back to the heart. • Veins and venules have a wide diameter to carry large volumes of blood. • Veins and venules have thin walls because the blood is at low pressures. • Low pressure blood tends to flow back down the veins due to gravity, so veins are equipped with internal valves. A cross section of a vein. Capillaries • Capillaries are the smallest blood vessels – they are so small that red blood cells can only pass through single file. • The thin walls of capillaries (only one cell thick) facilitate the exchange of nutrients and waste, along with oxygen and carbon dioxide. The Blood • Blood is a connective tissue and the only liquid tissue in the body. It is pumped through the blood vessels and lungs by the heart. • Blood is important for homeostasis. It carries oxygen and nutrients to tissues and takes away carbon dioxide and wastes. • White blood cells, which fight infections, are circulated through the body through the blood. Composition of Blood • Blood is composed of plasma, red blood cells, white blood cells, and platelets. • 55% of blood is composed of plasma, a watery fluid which contains proteins important for homeostasis and blood clotting. Red Blood Cells • Nearly 45% of blood is made up of red blood cells. • Red blood cells carry oxygen and carbon dioxide. They have an iron-containing protein called hemoglobin, which can bind to oxygen and carbon dioxide. • Red blood cells have a biconcave disc shape which allows them to squeeze through narrow capillaries to perform oxygen exchange. Notice the unique shape of these red blood cells. White Blood Cells • White blood cells fight infections. There are two main types: granulocytes and agranulocytes. • Granulocytes • Neutrophil: phagocytize bacteria and small particles • Eosinophil: kill parasites and regulate allergic responses • Basophil: regulate immune response by secreting histamine • Agranulocytes • Monocyte: differentiate into macrophages (phagocytize large particles) • Lymphocytes • T lymphocytes: kill virus-infected cells and cancers • B lymphocytes: produce antibodies Platelets • Platelets are small cell fragments that are produced in the bone marrow. They are important in homeostasis and healing of wounds. • If a blood vessel is punctured, platelets form a plug to prevent blood loss. They also secrete proteins which combine with other blood proteins to form a sticky mesh. This mesh entangles other cells to create a clot. Open and Closed Circulatory Systems • There are two types of circulatory systems: open and closed. • A closed circulatory system has blood contained within vessels. Most vertebrates (including humans) have a closed circulatory system. • An open circulatory system simply circulates blood within the main body cavity. Most insects and invertebrates have an open circulatory system. A fish (on the left) has a closed circulatory system. A crayfish (right) has an open circulatory system. Hearts of Vertebrates • Not all animals have hearts similar to those of humans. • Mammals (including humans) and birds have a complete four-chambered heart (2 atria, 2 ventricles). • Amphibians have a three-chambered heart (2 atria, 1 ventricle) with channels that reduce mixing of blood between the two circuits. Reptile hearts are similar, but the ventricle has an incomplete partition. • Fish have a two-chambered heart (1 atrium, 1 ventricle) that only pumps blood in one circuit. Circulatory Systems of Animals Pulmonary Circuit Systemic Circuit Fish Reptiles* and Amphibians Birds and Mammals *A reptile heart has a partially divided ventricle, but is still similar to the amphibian heart. Disorders of the Circulatory System • Heart Disease • A narrowing of the arteries due to buildup of cholesterol “plaques” inside the arteries. • Symptoms include chest pain, shortness of breath, high blood pressure, or exhaustion. • 82% of sufferers over 65 years old, men 2-5 times more likely than women, also associated with obesity. • Treated with exercise, special low-fat diets, or drugs which interfere with cholesterol intake. Disorders of the Circulatory System • Sickle Cell Anemia • Genetic (autosomal recessive) disorder which causes production of an abnormal form of hemoglobin, causing red blood cells to form “sickle” shapes and clog blood vessels. This causes tissue damage. • Symptoms include shortness of breath, bone pain, exhaustion, jaundice, and rapid heart rate. • The number of people with sickle cell anemia varies from country to country, but 75% of all cases occur in Africa. • Symptoms are lessened with folic acid supplements or blood transfusions. A bone marrow transplant is the only cure. Sources • http://www.google.com/ • http://en.wikipedia.org/ • Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGrawHill: 2007. • http://universe-review.ca/R10-19-animals.htm The Respiratory System Functions To take oxygen into the body and to remove carbon dioxide from the body. The respiratory system works in conjunction with the circulatory system. Deoxygenated blood is pumped through the lungs, where it picks up oxygen and releases carbon dioxide. Parts of the Respiratory System Nasal Cavity Mouth Pharynx Larynx Trachea Bronchi Right Lung Bronchioles Left Lung Bronchiole Alveoli Blood Vessel Alveolar Sac Breathing The process of breathing is called respiration. First, air is taken into the lungs by the process of inhalation. A large sheet of muscle under the lungs called the diaphragm contracts, increasing the volume and decreasing the pressure in the lungs about 2 mm Hg. Additional chest muscles may assist in this process. The air moves into the nasal cavity and then into the trachea. It then enters the lungs by passing through the bronchi, the bronchioles, and finally the alveoli, where gas exchange is performed. Breathing Finally, air is then forced out of the lungs, a process called exhalation. The diaphragm relaxes, and the elasticity of the organs and the chest cavity is usually enough to decrease the volume of the lungs and increase the pressure (by about 2 mm Hg) to force the air out. Chest muscles may also help in forced expiration. The Alveoli Alveoli are the tiny air sacs at the end of the bronchioles. Gas exchange takes place in the alveoli. They provide a huge surface area – 70-80 square meters – for efficient gas exchange. Alveoli have thin walls made out of single-layered epithelial tissue for maximum efficiency. They produce a compound called surfactant to prevent water surface tension from sticking the walls together. Capillaries line the sides of the alveoli. Oxygen and carbon dioxide can diffuse through the walls of the alveoli. Transport of Gases The blood transports oxygen and carbon dioxide to the lungs and to the body. Oxygen is primarily carried on a bright red, ironcontaining protein called hemoglobin that is in red blood cells. Carbon dioxide is carried in three different ways. Dissolved in plasma: 7% Carried by hemoglobin: 15-25% Bicarbonate ions: 62-72% Diseases of the Respiratory System Lung Cancer Caused by uncontrolled cell division of lung tissue. 27% of all cancer deaths are due to lung cancer, there are 220,000 new cases every year. It is much more likely to occur in smokers. Can cause difficulty breathing, coughing up blood, chest pain, fatigue, or difficulty swallowing. Treated with chemotherapy, radiation, or (if the tumor has not spread) surgical removal of the affected area of the lung. Tumor Diseases of the Respiratory System Asthma An inflammation of the trachea and bronchi that can (but not always) be caused by allergies. Tightness in chest, wheezing, and coughing are common symptoms. Severe cases can obstruct the airways and become life-threatening. Affects 20 million people in the U.S. each year. It is more common among children and people with allergies. Asthma cannot be cured, but it can be prevented by avoiding allergens and taking medication (often in inhalers). Sources Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGrawHill: 2007. http://www.google.com/ http://en.wikipedia.org/ http://www.nhlbi.nih.gov/health/healthtopics/topics/hlw/system.html http://www.medicinenet.com/lung_cancer/article.htm THE EXCRETORY SYSTEM FUNCTIONS To filter the blood and remove wastes. To keep the body under homeostasis by regulating the concentration of solutes in the blood. The excretory system consists of two kidneys and a bladder. The kidneys filter the blood and the bladder collects the wastes. The Kidney Cortex Medulla Renal Artery Renal Pelvis Renal Vein Ureter Interlobular Blood Vessels Arcuate Blood Vessels Interlobar Blood Vessels HOW THE KIDNEY WORKS 1 . Blood enters the renal artery, into the interlobar arteries, and then into the interlobular arteries in the cortex. 2. The blood flows into nephrons, which are structures located in the cortex and the medullae. The nephrons remove wastes and salts from the blood. 3. The blood flows back out into the interlobular veins, the interlobar veins, and finally into the renal vein, where it goes back to the heart. 4. The extracted wastes, known as urine, flow down to the bladder, where it accumulates and is periodically excreted. The Nephron Proximal Convoluted Tubule Efferent Arteriole Peritubular Capillary Nephron Loop Collecting Duct Interlobular Artery Interlobular Vein Glomerulus Afferent Arteriole Glomerular Capsule Distal Convoluted Tubule THE NEPHRON The nephrons are the main functional units of the kidneys. Each kidney contains about 1 million nephrons. 1 . Blood enter s via the interlobular ar teries. 2. The blood passes through a glomerulus, a cluster of capillaries contained within a glomerular capsule. The glomerulus filters out water and small molecules. 3. The blood flows by the proximal convoluted tubule, which reabsorbs cer tain substances such as water and glucose and also secretes organic wastes. 4. The blood then flows via the peritubular capillaries through the nephron loop, which controls the concentration of urine. 5. The last step of urine formation occurs when the blood passes by the distal convoluted tubule, which regulates the concentration of urine. The blood exits into the interlobular veins. 6. Wastes flow into the collecting duct and into the ureter. THE NEPHRON The nephron does several dif ferent jobs. Filtration is the filtering of substances from the blood by diffusion. It mainly occurs in the glomerular capsule. Reabsorption is the uptake of substances from the urine. Water, salts, glucose, amino acids, and proteins are actively transported back into the blood. The proximal convoluted tubule reabsorbs most of the wastes. Secretion is the active transport of substances into the urine. Hydrogen ions are secreted throughout the renal tubule, and other section secrete certain organic molecules. Excretion is the removal of wastes from the body. The final products of the kidneys, urine, flows down the ureters and collects in the bladder. The bladder periodically discharges the urine (micturition) when it is full. NITROGENOUS WASTES There are three main nitrogenous wastes in the urine. They are urea, uric acid, and ammonia. Dif ferent animal groups secrete dif ferent compounds in their urine. Ureotelic animals mainly secrete urea. Mammals, some cartilaginous fish, certain invertebrates, and adult amphibians are ureotelic. Uricotelic animals mainly secrete uric acid. Birds, most reptiles, and most terrestrial arthropods are uricotelic because uric acid can be safely stored in eggs. Ammoniotelic animals mainly secrete ammonia. Ammonia can only be eliminated by dissolution in large quantities of water, so ammoniotelic animals are primarily aquatic. Amphibian larvae, most fish, and other aquatic animals are ammoniotelic. DISEASES OF THE EXCRETORY SYSTEM Kidney stones Accumulations of solid salts or uric acid crystals that can get stuck in the kidney. Can cause severe kidney pain or blood in the urine. Different compositions of stones occur in different groups of people. They can form in people who do not drink enough water or whose diet is high in certain substances, such as calcium. They also may form in some people with metabolic disorders. About 60% of kidney stones are passed naturally. Smaller stones can be treated with drugs that dissolve the stones. Larger stones can be broken with external shockwaves (extracorporeal shockwave lithotripsy) or removed surgically. Dietary changes can alleviate some types of kidney stones. DISEASES OF THE EXCRETORY SYSTEM Gout Usually caused by an inability of the kidneys to eliminate uric acid or sometimes an overproduction of uric acid. The uric acid crystallizes in joints, causing friction and damage to the tissues. Joint pain is a common symptom, usually in the joint of the big toe, ankle or knee joint. The joint may redden and swell. Affects 1-2% of western people; older people, obese people, and diabetics are more susceptible. Treated with painkillers. Diets with low amounts of purine nucleotides and alcohol help prevent progression of the disease. SOURCES Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGraw -Hill: 2007. http://www.google.com/ http://en.wikipedia.org/ http://www.biology -questions-and-answers.com/the-excretory system.html * * * To recognize organisms and substances that would otherwise harm the body. * To protect the body from such organisms and substances. * * Bone marrow: produces blood cells, including white blood cells. * Lymph vessels: carry a watery fluid called lymph that contains white blood cells. That is filtered from surrounding tissues and is eventually mixed with blood. Lymph nodes may swell during an infection. * Lymph nodes: house white blood cells, interconnected by lymph vessels. * Thymus: helps produce T lymphocytes. * Peyer’s Patches: fight infections in intestine. * Spleen: houses large numbers of white blood cells and recycles old red blood cells. * Tonsils: fight infections in the throat. Lymph nodes, thymus and spleen. * * “Built in” immunity; coded * Immune response caused by exposure * General immune response, * Not coded for in DNA, but immune * Example: when the skin is * Specific responses to each pathogen; by DNA. such as inflammation and swelling. cut, the surrounding area swells up and becomes painful. to pathogens. system will “remember” how to fight them in the future. for example, different antibodies are produced against different bacteria. * Example: the immune system has trouble fighting smallpox at first, but once it fights the smallpox off, it will continue to do so and the person will never get smallpox again. * * Immunity developed after * The transmission of * Example: Once a person * Example: breast milk the body is infected and fights off the pathogen. gets strep throat, the immune system fights the infection. The person will be less prone to infection next time because the immune system has already fought strep throat. antibodies from one person to another. contains antibodies that protect the baby. * * Immunity created by * Immunity created by * Present in some degree at * Includes activation of T cells antibodies already floating in the blood plasma. all times. activities of white blood cells. and B cells. * Can create humoral immunity when activated cells produce antibodies. * * There are two different types of lymphocytes: B and T lymphocytes. * B (bursa derived) cells mature in the bone marrow. * Naïve B cells have not yet encountered pathogens. When they do encounter pathogens, they become memory B cells which will respond quickly to the same antigen by dividing. They are activated by helper T cells. * Plasma cells differentiate from B cells and produce large amounts of antibodies. * T (thymus) cells mature in the thymus. * Helper T cells detect foreign antigens, often presented to them by macrophages. * Cytotoxic T cells kill cancer cells and virus-infected cells. * Memory T cells “remember” previous encounters with antigens and alert other cells if the antigen is encountered again. * * Antibiotics are substances that are used to help treat infections. * Antibiotics kill bacteria and fungi in a variety of ways. They can inhibit transcription or translation, damage the cell wall, or bind to proteins. * Viruses are unaffected by antibiotics. Viruses have no internal processes to be targeted by antibiotics. They also reproduce inside other cells, which makes them difficult targets. Penicillin Ciprofloxacin Cephalexin * * Acquired Immunodeficiency Syndrome (AIDS) * Caused by the infection of the human immunodeficiency virus (HIV), a retrovirus which attacks white blood cells. * No symptoms at first, but later causes fever, chills, swollen lymph nodes, and increased frequency of infections. * 33.4 million people worldwide have AIDS. Drug addicts who share needles and sexually active people are more susceptible because the virus can only be transmitted through bodily fluids or sexual contact. * No cure yet, but infected people can live a fairly normal life by taking antiretroviral drugs. * * Leukemia * A cancer caused by uncontrolled production of white blood cells in the bone marrow. These are immature and incapable of fighting infection, and also crowd out other normal blood cells. * Symptoms include fatigue, mild fever, and mild hemophilia. * Causes 33% of all cancer cases in children. About 140,000 people in the United States suffer from leukemia. People exposed to carcinogens or highenergy radiation are at risk. * Treated with chemotherapy, radiation, or bone marrow transplants. Five-year survival rate is about 90%. Leukemic white blood cells. * * Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGrawHill: 2007. * http://www.google.com/ * http://en.wikipedia.org/ * http://www.lymphnotes.com/article.php/id/151/ * http://www.lymphomation.org/lymphatic.htm To provide support for the body and to provide solid points for skeletal muscle attachment. To protect delicate organs from physical damage. To house tissues that store nutrients and produce blood cells. Parts of a Long Bone Yellow Marrow Articular Cartilage Epiphysis Periosteum Medullary Cavity Diaphysis Blood Vessels Compact Bone Epiphyseal Plate (Growth Plate) Spongy Bone and Red Marrow The human skeleton is composed of 206 bones. Infants have more bones because some bones fuse together as a person grows up. Humans, other mammals, reptiles, birds, and amphibians have an endoskeleton – a skeleton composed of bones on the inside of their body. Bones are made form protein and calcium salts. Muscles are attached to the surface of the bones. Arthropods, on the other hand, have an exoskeleton – a skeleton composed of a shell on the outside of the body. The shell is usually made of chitin and cannot support as much weight as an endoskeleton. Muscles are attached on the inside of the exoskeleton. Some animals, such as mollusks, may have a hydrostatic skeleton - a skeleton composed of a fluid-filled internal cavity. Muscles create movement by compressing the fluid and utilizing hydraulic pressure. Bones provide a solid structure for muscles to pull on. Muscles contract when stimulated by a nervous impulse, moving the bones and tissues that are supported by the bones. Tendons firmly connect muscles to bones. They are made out of tough connective tissue, like cartilage. Ligaments connect bones to other bones. Like tendons, they are made of connective tissue. Osteoporosis A gradual loss of bone density. Symptoms can be subtle, but include bone pain (from small stress fractures), high frequency of broken bones, loss of height, or deformation of stress-bearing bones. More common among older women who have reached menopause as well as malnourished children who cannot get enough vitamin D. Treated with calcium or vitamin D supplements. Women who have reached menopause may be given artificial hormones. Osteogenesis imperfecta Brittle bones caused by an autosomal dominant mutation in the gene that codes for collagen, a protein found in bones. Rare, recessive forms of the disease also exist. Symptoms can include deformation of the bones, increased frequency of fractures, blue tint in the whites of the eyes, and deafness. Affects 1 per 20000 live births; more common in certain peoples of Zimbabwe and South Africa. Treated with physical therapy, surgery, physical aids, or nutritional supplements. Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGraw-Hill: 2007. http://www.google.com/ http://en.wikipedia.org/ www.ncbi.nlm.nih.gov » To regulate body functions by secreting chemicals called hormones, which influence the functions of other organs and tissues. » The endocrine system is very important in maintaining homeostasis as well as growth, development, and reproduction. Major Organs of the Endocrine System Hypothalamus Pineal Gland Pituitary Gland Thyroid Gland Thymus Parathyroid Gland Adrenal Gland Kidney Pancreas Ovary (only in females) Testis (only in males) » Hypothalamus: secretes gonadotropin-releasing hormone, which causes secretion of gonadotropins, which in turn increases reproductive activity. » Pituitary Gland: secretes growth hormone, which triggers cell division and elongation of epiphyseal plates of bones. » Pineal Gland: secretes melatonin, which controls circadian rhythms (sleep cycles). » Thyroid Gland: secretes thyroxine, which increases metabolic rate (rate of energy use of the body). » Parathyroid Glands: secrete parathyroid hormone, which increases the concentration of calcium ions and decreases the concentration of phosphate ions in the blood. Melatonin Structure of parathyroid hormone. Thyroxine » Thymus: secretes thymosin, which increases the growth rate of T lymphocytes. » Pancreas: secretes insulin, which increases storage of glucose. » Adrenal Glands: secrete epinephrine, which increases heart rate, dilates airways, and triggers the “fight or flight” response; it is secreted in response to stress. » Kidneys: secrete renin, which helps maintain blood pressure. » Ovaries: secrete estrogens, which causes development of female characteristics such as breast and uterus growth. » Testes: secrete testosterones, which causes development of male characteristics such as enlarged muscle and body hair. Left: Estradiol, an estrogen Right: Testosterone. » Homeostasis is the body’s ability to maintain a stable internal environment. » The endocrine system secretes hormones to carefully control internal conditions. » Negative feedback is used by the endocrine system to regulate the secretion of hormones to maintain homeostasis. » Negative feedback helps regulate secretion of hormones. » Endocrine glands reduce production of hormones when it senses these stimuli. ˃ Change in concentration of hormone or in the process the hormone controls. ˃ Action the hormone has on the body. ˃ Stimulation by nervous system in response to secretion of the hormone. » This helps keep internal processes relatively constant. » Example: the pancreas secretes less insulin when glucose concentration is low, and secretes more insulin when glucose concentration is high. » Diabetes ˃ An inability of the pancreas to produce enough insulin. There are two types of diabetes: Type I and Type II. » Type I Diabetes ˃ Caused by the autoimmune destruction of the pancreatic islet cells that produce insulin. Usually present from an early age. ˃ Symptoms include persistent thirst and hunger, weight loss, numbness in feet, fruity breath, or rapid breathing. Glucose is present in the urine, and this is used to detect both types of diabetes. Coma and death can result if untreated. ˃ It is more common among Hispanics and Africans, as well as young children. ˃ Treated with artificial insulin injections and a diet to control glucose intake. A pancreas transplant can be done, but it is rather difficult and the patient still has to take immunosuppressive drugs. » Type II Diabetes ˃ Caused when tissues fail to respond correctly when insulin is secreted (insulin resistance). Adequate amounts of insulin are produced, however. ˃ Symptoms include thirst, hunger, numbness in hands or feet, blurred vision, or increased urination. ˃ Native Americans, Pacific Islanders, and South Asians are more likely to have Type II diabetes. People can be genetically predisposed to have it. Type II diabetes is also much more common among obese people, and is one of the fastest growing health problems. ˃ Treated with weight loss and special diets, as well as drugs that increase responsiveness to insulin. » Gigantism ˃ Caused by an overproduction of growth hormone, usually due to a tumor on the pituitary gland. Robert Wadlow, the tallest man ever, had this condition. ˃ Symptoms include extremely large size, delayed puberty, large hands, double vision, weakness, or (in females) irregular menstruation. ˃ The demographics of gigantism are poorly documented but it can run in families. ˃ Treated with removal of pituitary gland tumor (if present) or drugs that inhibit growth hormone. Robert Wadlow (8’ 11”), with his father (5’ 11”). Mamadou N’diaye (7’ 5”, 17 years old as of 2012) had a golf- ball-sized pituitary gland tumor. » Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGrawHill: 2007. » http://www.google.com/ » http://en.wikipedia.org/ » www.ncbi.nlm.nih.gov/ » http://www.diabetes.org/diabetes-basics/diabetesstatistics/ » http://www.cbsnews.com/8301-31751_162-5737071510391697/mamadou-ndiaye-7-foot-5-high-schoolbasketball-player/ To collect information about the outside world so it can be relayed to and interpreted by the nervous system. The senses include touch (skin), taste, (tongue), sight (eyes), hearing (ears), and smelling (nose). These senses are all important in interacting with the outside environment. The Eye Sclera Iris Retina Vitreous Humor Cornea Pupil Aqueous Humor Lens Optic Nerve Rhodopsin is a protein that found in the retina. It participates in cell signaling in the eye and is essential to sight. Rhodopsin is a photoreceptor protein. When light hits rhodopsin, it changes shape to release opsin. Opsin becomes an active enzyme and catalyzes the formation of other proteins in a rapid cell signaling pathway. At the end of the pathway, the cell membrane is hyperpolarized and stimulates adjacent nerve cells which can relayed to the brain. Mechanoreceptors Thermoreceptors These are “touch receptors”. They detect changes in pressure or movement and are found all over the skin and are concentrated on the fingertips. They are also found in the ears (to detect changes in air pressure which create sound). Thermoreceptors sense temperature. They are also present all over the skin, but are especially numerous on the fingertips and the lips. Chemoreceptors Various chemicals can be detected by chemoreceptors. Each chemoreceptor is usually adapted to detect one type of chemical (acid, base, salt, etc.). They occur on the surface of the tongue (housed inside the taste buds) and the roof of the nasal cavity (to detect smell). Photoreceptors Photoreceptors detect light. They are present in the retina of the eyes. Humans have several different types of photoreceptors to detect different colors and see in dim light. Pain Receptors Pain, usually caused by trauma to the body, is detected by pain receptors. They can be found in large numbers in the fingertips, lips, and tongue, although they occur throughout the body. Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGraw-Hill: 2007. http://www.google.com/ http://en.wikipedia.org/ The Muscular System Functions • To move parts of the body by contraction. This includes: ▫ ▫ ▫ ▫ ▫ Moving the limbs Pushing food through digestive system Breathing Heartbeat And more! Sarcomere A sarcomere is the basic unit of a muscle cell. Actin I Band Head of Myosin Filament Myosin A Band Z Line H Zone M Line Types of Muscle Skeletal Muscle has distinct striations and an orderly structure. It is made of large, multinucleated cells and is under voluntary control. It is found in skeletal muscles that are attached to bones. Cardiac Muscle is also striated but has a less organized structure. The cells each have one nucleus and are under involuntary control. The cells are separated by intercalated disks which are a type of cellular junction that allows movement of nervous impulses. It is found in the heart. Smooth Muscle is not striated and has a relatively unorganized structure. The cells each have a single nucleus and are under involuntary control. Smooth muscle is found in internal organs and ducts. How a Muscle Works • 1. A neuron contacts a muscle cell at a neuromuscular junction. To signal the muscle to contract, the neuron releases acetylcholine, a neurotransmitter. • 2. Acetylcholine stimulates the sarcoplasmic reticulum (modified smooth endoplasmic reticulum) to release calcium ions. • 3. The calcium ions bind to proteins located on the actin filaments. This allows the heads of the myosin filaments to bind to the actin, forming cross bridges. How a Muscle Works • 4. The heads of the myosin filaments, powered by ATP, tug on the actin filaments. This pulls the filaments closer together, causing the muscle to contract. • 5. To relax the muscle, acetylcholine secretion by the neuron is halted and an enzyme in the neuromuscular junction quickly digests the acetylcholine. • 6. The calcium ions are actively transported back into the sarcoplasmic reticulum by an ATP-powered calcium pump. The myosin-actin cross bridges disconnect and the elastic muscle relaxes. Diseases of the Muscular System • Duchenne Muscular Dystrophy ▫ A recessive, X-linked mutation in a gene coding for the protein dystrophin causes this disease. The mutation causes the muscles to progressively degenerate. It mostly affects boys. ▫ Symptoms include fatigue, lack of motor skills, weakness, inability to walk, or skeletal deformities. ▫ 1/3500 boys worldwide are affected. The disease is genetic so it may run in families. ▫ No treatment yet, but physical therapy and physical aids, such as braces or wheelchairs, can help people with Duchenne muscular dystrophy. Diseases of the Muscular System • Tetanus (“Lockjaw”) ▫ Caused by the bacterium Clostridium tetani, which produces a chemical which inhibits the enzyme that digests acetylcholine. The muscles become continuously activated by acetylcholine. ▫ Symptoms include muscle spasms, fever, sweating, or continuous contraction of muscles. Severe cases can stop breathing. ▫ More common in 3rd world countries without adequate sanitation. ▫ Treated with antibiotics and muscle relaxants. Vaccines for tetanus are usually quite effective. Sources • Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGrawHill: 2007. • http://www.google.com/ • http://en.wikipedia.org/ • www.genome.gov/19518854 • www.rightdiagnosis.com/d/duchennemd/stats.htm • www.ncbi.nlm.nih.gov/ • Kapit, Wynn, and Lawrence M. Elson. The Anatomy Coloring Book. United States, Wynn Kapit and Lawrence M. Elson: 1993. Functions To receive and process information from the outside world (usually collected by the senses system). To signal the rest of the body to respond accordingly to external and internal stimuli. The nervous system primarily consists of neurons, which are cells that are modified to carry information. The Neuron Synapse (space between adjacent neurons) Dendrite Chromatophilic Substance Nucleus Schwann Cell Axon Node of Ranvier Reflex Arc 2. A sensory (afferent) neuron sends a message to the spinal cord. 1. Stimuli are detected. 4. The efferent neuron relays a message to an effector organ, usually a muscle or a gland. 5. The effector organ reacts to the stimulus. 3. The spinal cord processes the information and an interneuron transmits a message to a motor (efferent) neuron. The Central and Peripheral Divisions The central nervous system consists of the brain (itself made of the cerebrum, cerebellum, brainstem, and diencephalon) and the spinal cord. It serves to process and store information as well as output information to the rest of the body. The peripheral nervous system is made of the nerves and sensory receptors scattered throughout the body. It collects information and sends it to the central nervous system. The peripheral nervous system also relays the central nervous system’s messages to the rest of the body. Neurotransmission A neuron pumps sodium ions outside the neuron and potassium ions inside the neuron using an active transport pump (sodium-potassium pump). This creates a membrane potential. When not excited, the neuron’s membrane potential is at its resting potential (-70 millivolts). 1. Another neuron’s axon stimulates the neuron’s dendrites with neurotransmitters. 2. The stimulation opens ion channels in the cell membrane. If the stimulation is great enough, the threshold potential (-55 mV) is reached and an action potential is started in the neuron. Neurotransmission 3. Voltage-gated ion channels open, allowing sodium ions in and depolarizing the neuron. 4. Potassium ions move out of the neuron, repolarizing the neuron. The impulse moves down the axon of the neuron. 5. While the impulse travels down the axon, the neuron cannot be stimulated again for a short period of time called the refractory period. 6. When the impulse reaches the end of the axon, the neuron secretes neurotransmitters into the synapse between the next neuron, which starts the cycle over again. Neurotransmitters Neurotransmitters are compounds secreted by neurons across the synapses to communicate with other neurons. Different neurotransmitters evoke different responses. Excitatory neurotransmitters facilitate the depolarization of the next neuron. These include: Acetylcholine Epinephrine Norepinephrine Neurotransmitters Inhibitory neurotransmitters inhibit the depolarization of the nerve cell membrane. These include: Dopamine GABA Glycine Serotonin Endorphins Diseases of the Nervous System Alzheimer’s Disease A progressive loss of mental function due to protein deposits (amyloid plaques) that build up in brain tissue. It is most likely caused by many distinct factors. Symptoms include amnesia, changes in mood, insomnia, poor judgment, and difficulty in counting and other everyday mental activities. 35 million people worldwide have Alzheimer’s. It mostly occurs in older (>60 years old) people. No cure exists yet, but there is a variety of medications that can partly alleviate the symptoms. Diseases of the Nervous System Poliomyelitis A viral infection, caused by the poliovirus, that can attack the central nervous system. Less severe infections can cause diarrhea, fever, and stiffness. Severe infections cause fever, abnormal sensations, muscle weakness, muscle spasms, and possible paralysis. Some forms can be asymptomatic. Poliomyelitis often affects younger children, especially in rural areas. There are about 1,000 cases every year. There is no cure for poliomyelitis, but painkillers, braces, and wheelchairs can help those affected by it. However, it can be prevented by vaccination. The poliovirus. Sources Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGrawHill: 2007. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001 767/ www.alzinfo.org/Alzheimers_Disease http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002 375/ http://www.google.com/ http://en.wikipedia.org/ To produce offspring. To produce eggs/sperm that will fertilize each other to produce a zygote. To nourish the embryo as it is growing. Asexual Sexual Rapid and requires relatively simple processes. Offspring are nearly identical to parents, leading to lack of genetic diversity that makes species extinction-prone. Some echinoderms, sponges, worms, insects, and reptiles reproduce asexually. Time consuming and requires many different processes such as meiosis. Offspring are genetically diverse which allows species to adapt to changes. Most animals have some form of sexual reproduction, although the asexual form may dominate in simpler animals. Spermatogenesis Spermatogenesis is the production of sperm. First meiotic division and crossing over Second meiotic division Maturation Secondary Spermatocyte Primary Spermatocyte Spermatid Spermatozoa Oogenesis Oogenesis is the production of eggs. First meiotic division and crossing over Fertilization by sperm Secondary Oocyte Second meiotic division Zygote Second Polar Body Primary Oocyte First Polar Body Spermatogenesis produces four sperm cells for every primary spermatocyte. Oogenesis produces one egg cell for every primary oocyte, with the cytoplasm dividing unequally to form two polar bodies. This ensures that the single egg has all the necessary cellular components to survive. The menstrual cycle is used by great apes and humans. Animals that menstruate will shed the endometrium (inner lining) of the uterus if the egg is not fertilized. They also can be sexually active at any time of the cycle. The estrous cycle is used by most other animals. Animals that used the estrous cycle reabsorb the endometrium if the egg is left unfertilized, and they are only active during certain stages of the estrous cycle. Humans and primates use the menstrual cycle. It is split into the ovarian cycle and the uterine cycle. › The ovarian cycle occurs in the ovaries. › The anterior pituitary gland secretes luteinizing hormone and follicle-stimulating hormone, causing an oocyte to form in a follicle in the ovaries. › At about 14 days into the cycle, the levels of luteinizing hormone and follicle-stimulating hormone peak, causing the follicle to rupture, and ovulation (release of the egg into the uterine tube) occurs. › The ruptured follicle becomes a corpus luteum, which secretes estrogen and progesterone. These act as negative feedback that causes the pituitary gland to stop secreting hormones. › The corpus luteum degenerates and becomes a corpus albicans in about 28 days, and the cycle starts over again. The other part of the menstrual cycle is the uterine cycle. › The uterine cycle occurs in the uterus. › Growing levels of estrogen and progesterone cause the endometrium (lining of the uterus) to become thicker and grow more blood vessels. › Estrogen levels peak at about 14 days into the cycle, causing rapid growth. › The corpus luteum continues to secrete estrogen and progesterone. The endometrium continues to grow until about 28 days, when the corpus luteum entirely degenerates and the endometrium peels off and is ejected. When the embryo is first fertilized by the sperm, it starts to divide (cleavage) into a solid ball of cells called a morula. As the morula continues to grow, it becomes a hollow ball of cells called a blastula. The blastula later gastrulates (caves in) to form a gastrula, a double-layered ball of cells with a pore (blastopore) at one end. Finally, organogenesis occurs, which is the differentiation of cells into organs. Left: Morula. Left: Blastula. Left: Gastrula. The gastrula is divided into three germ layers: the endoderm, mesoderm, and ectoderm. The endoderm is the inner layer of cells. It forms the inner lining of the digestive tract, stomach, intestines, colon, liver, lungs, and urinary bladder. The mesoderm is the middle layer of cells. It forms the skeletal muscles, skeleton, heart, blood, kidneys, and spleen. The ectoderm is the outer layer of cells. It forms the upper layer of skin, the lenses of the eyes, and the nervous system. Shier, David, Jackie Butler, and Ricki Lewis. Hole’s Human Anatomy and Physiology. New York, McGraw-Hill: 2007. http://www.google.com/ http://en.wikipedia.org/ http://answers.yahoo.com/question/index?qid=20 070828195917AAE6j0y http://www.embryology.ch/anglais/evorimplantati on/furchung01.html