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Blood Chapter 10 Blood - River of Life • The only fluid tissue in the human body • Contains both cellular and liquid components • Classified as a connective tissue – Living blood cells: erythrocytes, leukocytes and platelets are called formed elements – Plasma is the non-living matrix and fibrous proteins are only visible during clotting Blood Composition • If we spin a sample of blood in a centrifuge • The heavier formed elements will be at the bottom – Mostly composed of erythrocytes - RBCs • The less dense plasma remains at the top • A thin whitish layer in the middle is called the buffy coat – Contains leukocytes and platelets Blood Composition • 55% is blood plasma • 45% is erythrocytes • 1% is the buffy coat (platelets and leukocytes) Blood Characteristics • • • • Sticky, opaque fluid Scarlet red – oxygen rich blood Dark red – oxygen poor blood Volume = 8% of your body weight – 4-5 L in females & 5-6 L (1.5 gallons) in males • More dense than water • Slightly basic with a pH between 7.35-7.45 • Temperature is slightly higher than body temperature (100.4) Blood - River of Life • Functions of blood 1. Distribution – – Delivering oxygen and nutrients Transporting wastes and hormones 2. Regulation – Maintaining adequate fluid volume, normal pH, body temperature 3. Protection – Prevent infections and blood loss by forming clots Blood Plasma • Composition of plasma – Mostly water (90%) – Over 100 different dissolved solutes (10%) • • • • • • Plasma proteins Nutrients Electrolytes (ions) Respiratory gases Hormones Metabolic wastes Formed Elements • • • • Erythrocytes = red blood cells (RBCs) Leukocytes = white blood cells Platelets = cell fragments Two of the three are not even true cells – Erythrocytes have no nuclei or organelles – Platelets are cell fragments Erythrocytes – Red Blood Cells (RBCs) • Small cells that are shaped like biconcave discs with depressed centers • Lack a nucleus (anucleate) and have no organelles • Contain the protein hemoglobin that gives them their red color and carries the oxygen • Cannot grow or divide (amitotic) • Most numerous cells in the blood • 12 – 18 g of hemoglobin per 100 mL of blood The Fate of the RBCs • Life span of 100 to 120 days • Without a nucleus they are unable to divide, grow, or synthesize proteins and eventually begin to wear out • Eliminated by macrophages in the spleen or liver Erythrocyte Disorders • • Anemia – Condition in which the blood has abnormally low oxygen carrying capacity – Symptoms include fatigued, pallor, shortness of breath and cold chills Three types of anemia: 1. Insufficient number of RBC (Hemorrhagic or hemolytic anemia) • Results from blood loss, excessive RBC destruction and bone marrow failure Erythrocyte Disorders 2. Low hemoglobin count (Irondeficiency anemia) • Results from inadequate intake of iron-containing foods in diet 3. Abnormal hemoglobin (Sickle-cell anemia) • Results from having an abnormal hemoglobin shape that causes the RBC to be crescent shaped; they tend to rupture easily and dam up small blood vessels; usually genetic Leukocytes (1%) • White blood cells (WBCs) • Complete cells – Contain nuclei and organelles – No hemoglobin • Live for days, months or years • The “mobile army” of the circulatory system – Defend against bacteria, viruses, parasites, toxins and tumor cells • Formed in bone marrow Leukocytes • Classified in two categories based on visible granules – Granulocytes • Neutrophils • Eosinophils • Basophils • • • • – Agranulocytes • Lymphocytes (B and T) • Monocytes From most abundant to least abundant Neutrophil Lymphocyte Monocytes Eosinophils Basophils Never let monkeys eat bananas Normal WBC levels = 4,000 - 11,000 cells/mm3 Granulocytes • Neutrophils (50-70% of WBCs) – Most numerous – Fine granules that stain lilac – Body’s bacteria slayers by phagocytosis – Numbers increase explosively during an acute bacterial infection such as appendicitis and meningitis. – Positive chemotaxis - chemically attracted to sites of inflammation Granulocytes • Eosinophils (2-4% of WBCs) – Deep red nucleus with two lobes – Large, coarse granules stain brick red – Granules are packed with lysosomes and digestive enzymes – Attack parasitic worms such as flatworms and roundworms that are too large to be phagocytized – Gather around and release enzymes – Also play a role in allergies and asthma Granulocytes • Basophils (rare-1% of WBCs) – Deep purple nucleus – Large, coarse histamine containing granules that stain purplish black • Histamine is an inflammatory chemical that acts as a vasodilator (dilate blood vessels) and attracts other WBCs to the inflamed site • Antihistamines counter this effect • INFLAMMATION! Agranulocytes • Lack visible granules • Similar in structure but different in functions • Lymphocytes (25% of WBCs) – Large dark purple spherical nucleus that occupies most of the cell – Most of them are found in the lymphoid tissues where they play a crucial role in immunity – T lymphocytes – function in the immune response by acting directly against virus-infected cells and tumor cells – B lymphocytes – give rise to plasma cells which produce antibodies (immunoglobulins) that are released to the blood Agranulocytes • Monocytes (3-8% of WBCs) – Largest leukocytes – Blue cytoplasm and a dark purple nucleus – Differentiate into macrophages which are active phagocytes – Crucial in the body’s defense against viruses, bacteria and chronic infections such as tuberculosis – Also activate lymphocytes to mount the immune response Leukocyte Disorders – Leukemia • Cancer involving white blood cells – Serious acute forms usually affect children – Chronic leukemia affects elderly people • Tremendous numbers of leukocytes are produced that are nonfunctional and cannot defend the body • Red bone marrow becomes totally occupied by cancerous leukocytes and flood the bloodstream • Symptoms include severe anemia, bleeding problems, fever, weight loss, bone pain • Leukemia is fatal without treatment usually due to internal hemorrhages and infections Platelets • Not real cells • Made of cytoplasmic fragments of other blood cells • Contain an array of chemicals that act in the clotting process when a blood vessel is broken • Stick to the damaged area and form a temporary plug that helps seal the break • Degenerate in about 10 days • Normal platelet count is between 150,000 – 400,000 per microliter Hemostasis • Stoppage of blood flow in a broken blood vessel by a series of reactions • Fast, localized and controlled process – Occurs in 3-6 minutes • Three steps occur in rapid sequence to form a clot 1. 2. 3. Vascular spasms (vasoconstriction) Platelet plug formation Coagulation (blood clotting) Undesirable Clotting • Thrombus – A clot in an unbroken blood vessel – If the clot is large enough it may block circulation and lead to death of the tissues – Can be deadly in areas like the heart Undesirable Clotting • Embolus – If the thrombus breaks away and floats freely in the bloodstream – Not a problem until becomes trapped in narrow blood vessel then it becomes an embolism • Pulmonary embolism - trapped in the lungs • Cerebral embolism – clot in the brain (can cause a stroke) Bleeding Disorders • Hemophilia (Bleeder’s Disease) – – – – – Hereditary bleeding disorders Symptoms begin early in life Lack normal clotting factors Prolonged bleeding into tissues that can be life threatening Transfusions of fresh plasma can manage the condition Human Blood Groups • People have different blood types and transfusion of incompatible blood can be fatal • Erythrocytes contain highly specific proteins on their external surface which identify each of us as unique from all others • Proteins serve as antigens a substance that the body recognizes as foreign Human Blood Groups • The immune system makes antibodies against the other types of RBCs. • If a RBC with a foreign antigen was present the antibodies in the serum would cause the RBCs to clump and be destroyed Human Blood Groups • There are at least 30 varieties of red blood cell antigens in humans • The presence or absence of each antigen allows each person’s blood cells to be classified into several different blood groups • The most vigorous transfusion reactions are caused by antigens determining the ABO blood group and Rh blood group Transfusions • The circulatory system is designed to minimize the effects of blood loss • Large losses of blood have serious consequences – Loss of 15 to 30 percent causes weakness and pallor – Loss of over 30 percent causes severe shock, which can be fatal • Transfusions are the only way to replace blood quickly Transfusions • When mismatched blood is infused a transfusion reaction occurs • The donor’s red blood cells are attacked by the recipient’s plasma antibodies and clump (agglutination) • Agglutination of the foreign RBCs clogs small blood vessels and begin to rupture (lyse) or are destroyed by phagocytes • Transfusion reactions can cause fever, chills, low blood pressure, rapid heartbeat, nausea, vomiting and general toxicity ABO Blood Groups • Based on the inheritance of the presence or absence of two antigens – Type A and Type B • Blood type can be type A, B, AB, or O – Type O = lack of both antigens (most common) – Type AB = presence of both A and B antigens (least common) – Type A = presence of type A antigen – Type B = presence of type B antigen ABO Blood Groups • Unique to the ABO blood groups is the presence in the plasma of antibodies that act against RBCs carrying antigens that are not present on a person’s own red blood cells ABO Blood Groups • A person with neither the A or the B (type O) possesses both anti-A and anti-B antibodies • A person with type A blood would have anti-B antibodies • A person with type B blood would have anti-A antibodies • Neither antibody is produced by type AB individuals Rh Blood Groups • Rh antigen (agglutinogen D) was originally identified in rhesus monkeys • Most Americans are Rh+ (85%); they carry the D antigen • Unlike ABO, there are no anti-Rh antibodies formed in the blood of Rh • If a Rh - person receives Rh+ blood the immune system begins producing antibodies against the foreign antigen • Red blood cells do not get destroyed the first transfusion but the second time a reaction occurs and the RBCs would be attacked Rh Dangers During Pregnancy • Dangerous when the mother is Rh – and the baby is Rh + • First pregnancy usually proceeds without problems but the mother’s immune system gets exposed and starts making antibodies • If she is treated with RhoGAM (anti-Rh antigens) before or shortly after she gives birth her immune system will be blocked • If she is not treated and becomes pregnant with a Rh+ baby, her antibodies will pass through the placenta and destroy the baby’s RBCs – a condition known as hemolytic disease of the newborn Blood Typing • Blood is “typed” by using antibodies that will cause blood with certain proteins to clump (agglutination) before giving a transfusion • It is crucial to determine the blood group of both the donor and the recipient before blood is transfused • Blood samples are mixed with anti-A antigen serum and anti-B antigen serum • Cross matching tests for agglutination of the donor RBCs by the recipients serum Blood Typing • A person’s ABO and Rh blood type are usually reported together like O+ or A• People with type O are universal donors because they do not have either A or B antigens • People with type AB are universal recipients because they do not have any antibodies against either A or B antigens Genetics of Blood Typing • Blood type is established by specific genes inherited – One blood type gene from your mother and one from your father • Two genes determine the blood type by causing the presence or absence of the Type A and Type B antigen molecules on the red blood cells. • The blood type gene has three different versions of alleles: – IA results in A antigen on the red blood cells – IB results in B antigen on the red blood cells – i does not result in either antigen Genetics of Blood Typing • Everyone has two copies of these genes, so there are six possible combinations of alleles (called genotypes): – – – – IA IA and IA i IB IB and IB i IA IB ii Type A blood Type B blood Type AB blood Type O blood • In a heterozygous IA i person, which allele is dominant, IA or i? Explain your reasoning. Genetics of Blood Typing • Each biological parent gives one of their two ABO alleles to their child. • For example, a mother who is blood type O has genotype ii and can only give an i allele to her son or daughter. • A father who is blood type AB could give either an IA or an IB allele to his son or daughter. • This couple could have children of either blood type A (i from mother and IA from father) or blood type B (i from mother and IB from father). • Genetics of Blood Typing Genetics of Blood Typing 1. Determine the possible genotypes & phenotypes with respect to blood type for a couple who's blood types are homozygous A & heterozygous B. Genotypes: 50% IAIB; 50% Iai Phenotypes: type AB and A (heterozygous) Genetics of Blood Typing 2. What are the possible blood types of a child who's parents are both heterozygous for "B" blood type? Phenotypes: Type B and Type O Genetics of Blood Typing 3. What are the chances of a man with Type AB and a woman with Type A having a child with Type O? Answer: 0% Genetics of Blood Typing 4. A test was done to determine the biological father of a child. The child is blood type A and the mother is blood type B. Male #1 has a blood type O & male #2 has blood type AB. Which male is the biological father? Child ‘s blood type A Mother’s blood type B Possible offspring of woman & male # 1 Possible offspring of Woman & male # 2. Child is type A so male # 1 cannot be the father, but male # 2 could be. Blood Typing