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Chapter 10 - Blood • The only fluid tissue in the human body • Classified as a complex connective tissue • COMPONENTS: – Living cells = formed elements (RBC, WBC, Platelets) – Non-living fluid matrix = PLASMA (straw colored) 1 2 Physical Characteristics of Blood • Color range – Oxygen-rich blood is scarlet red – Oxygen-poor blood is dull red (NOT BLUE) • Sticky, opaque, with a metallic taste • Blood accounts for approx. 8% of your body weight • Volume in healthy men = 5.6 Liters (6 quarts) • pH must remain between 7.35–7.45 • Blood temperature is slightly higher than body temperature at about 100.4 degrees F • Heavier than water & 5x thicker (VISCOUS) 3 Blood Plasma • Liquid part of blood - Composed of approximately 90% water • Includes many (over 100) dissolved substances – Nutrients,Salts (electrolytes),Respiratory gases – Hormones, Plasma proteins made by liver, Waste products • Carries the Formed Elements – Erythrocytes = Red blood cells (RBC) – Leukocytes = White blood cells (WBC) – Platelets = Cell fragments 4 Plasma Proteins-Most abundant solutes in plasma • Albumin – Regulates osmotic pressure (helps to keep water in the bloodstream) • Clotting proteins – Help to stop blood loss when a blood vessel is injured • Antibodies – Help protect the body from pathogens • *When blood protein levels drop the liver is stimulated to make more proteins* 5 Photomicrograph of a Blood Smear 6 Figure 10.2 Characteristics of Formed Elements of the Blood 7 Table 10.2 Characteristics of Formed Elements of the Blood 8 Table 10.2 Erythrocytes (Red Blood Cells) • The main function is to carry oxygen to the cells of the body • Anatomy of circulating erythrocytes – Biconcave disks – Essentially bags of hemoglobin • HEMOGLOBIN- Iron bearing protein that Transports oxygen – Anucleate (no nucleus) • Outnumber white blood cells 1000:1 • Stay inside blood vessels • Contain no mitochondria, use anaerobic respiration 9 Hemoglobin • Iron-containing protein • Binds strongly to oxygen • Each erythrocyte (RBC) has 250 million hemoglobin molecules • Each RBC can carry 1 billion molecules of oxgen Homeostatic Imbalances 1) Anemia – Decrease in the oxygen-carrying ability of the of the blood. 2) Sickle Cell Anemia (SCA) – Genetic defect leads to abnormal hemoglobin which becomes sharp and produces a sickle shaped RBC. 10 Leukocytes (White Blood Cells) • Crucial in the body’s defense against disease • These are complete cells, with a nucleus and organelles • Able to move into and out of blood vessels (diapedesis) • Can respond to chemicals released by damaged tissues or infection (positive chemotaxis) • Can move by amoeboid motion 11 Leukocyte Levels in the Blood • Normal levels are between 4,000 and 11,000 cells per millimeter cubed. • Abnormal leukocyte levels – Leukemia “White Blood” • Bone marrow becomes cancerous • Huge #’s of WBC’s are produced at a rapid pace but are immature and ineffective – Leukocytosis (Normal response to infectious threats) • Above 11,000 leukocytes/mm3 • Generally indicates an infection (bacterial or viral) in body – Leukopenia • Abnormally low leukocyte level • Commonly caused by certain drugs (corticosteriods &12 anticancer agents) Types of Leukocytes • Granulocytes – Granules in their cytoplasm can be stained – Include neutrophils, eosinophils, and basophils • Agranulocytes – Lack visible cytoplasmic granules – Include lymphocytes and monocytes 13 Granulocytes • Neutrophils – Multilobed nucleus with fine granules – Active phagocytes at active sites of infection – Increase rapidly during short term infection • Basophils – Have histamine-containing granules (vasodilators) – Initiate inflammation • Eosinophils – Large brick-red cytoplasmic granules – Found in repsonse to allergies and parasitic worms – Play a complex role in allergy attacks 14 Agranulocytes • Lymphocytes (B & T) – Nucleus fills most of the cell – B produce antibodies – T involved in graft rejection, fighting tumors and viruses via direct cell attack. • Monocytes – Largest of the white blood cells – Function as active phagocytes that eventually become macrophages in tissues (Longterm “clean up team”) – Important in fighting chronic infection (Ex. Tuberculosis) 15 Platelets • Not considered complete cells but cell fragments • Derived from ruptured multinucleate cells (megakaryocytes) • Needed for the clotting process • Normal platelet count = 300,000/mm3 16 Hematopoiesis • Blood cell formation • Occurs in red bone marrow (epiphyses of humerus and femur) • All blood cells are derived from a common stem cell (hemocytoblast) • Hemocytoblast differentiation – Lymphoid stem cell produces lymphocytes – Myeloid stem cell produces other formed elements 17 Fate of Erythrocytes • Young RBC’s have a nucleus, the DNA directs the formation of hemoglobin. • Once mature, organelles are ejected. • Unable to divide, grow, or synthesize proteins (no DNA) • Wear out in 100 to 120 days, become rigid and fall apart • When worn out, are eliminated by phagocytes in the spleen or liver • Lost cells are replaced by division of hemocytoblasts 18 Control of Erythrocyte Production • Rate is controlled by a hormone (erythropoietin) • Kidneys produce most erythropoietin as a response to reduced oxygen levels in the blood • Homeostasis is maintained by negative feedback from blood oxygen levels • Leukocytes (WBC’s) & Platelets are stimulated by colony stimulating factors (csf) and interleukins. • Thrombopoeitin also stimulates an increase of platelets. 19 Control of Erythrocyte Production Figure20 10.5 Hemostasis • Stoppage of blood flow • Result of a break in a blood vessel • Hemostasis involves three phases 1. Vascular spasms- Immediate response is vasoconstriction. They narrow the blood vessel decreasing blood less. 2. Platelet Plug Forms- Platelets become “sticky” and cling to the damaged site. 3. Coagulation – Meshwork of fibrin forms the basis of the clot. 21 Blood Clotting • Blood usually clots within 3 to 6 minutes • The clot remains as endothelium regenerates • The clot is broken down after tissue repair Fibrin Clot 22 Homeostatic Imbalances in Clotting • Thrombus – A clot in an unbroken blood vessel, often legs – Can be deadly in areas like the heart (coronary thrombosis) • Embolus – A thrombus that breaks away and floats freely in the bloodstream – Can later clog vessels in critical areas such as the brain (cerebral embolus may = stroke) 23 Bleeding Disorders • Thrombocytopenia – Platelet deficiency – Even normal movements can cause bleeding from small blood vessels that require platelets for clotting – Petechiae – small purplish blotches on skin – May be caused by decrease in vitamin K – needed for clotting factors or from any condition that suppresses the bone marrow. • People at risk for clots monitor K levels • Hemophilia- “bleeder’s disease” – Hereditary bleeding disorder – All normal clotting factors are missing – Given transfusions of fresh plasma or purified clotting factors. 24 Blood Groups and Transfusions • Large losses of blood have serious consequences – Loss of 15 to 30 percent causes weakness – Loss of over 30 percent causes shock, which can be fatal • Transfusions are the only way to replace blood quickly • Transfused blood must be of the same blood group • Blood can be stored for approximately 35 days 25 Human Blood Groups • Blood contains genetically determined proteins (antigens) embedded in the plasma membranes of RBC’s • A foreign protein (antigen) may be attacked by the immune system • Blood is “typed” by using antibodies found in plasma that will cause blood with certain proteins to clump (agglutination) 26 Human Blood Groups • There are over 30 common red blood cell antigens (proteins) • The most vigorous transfusion reactions are caused by ABO and Rh blood group antigens • Mis-match can lead to severe kidney damage and shutdown • Not immediately fatal 27 ABO Blood Groups • Based on the presence or absence of two antigens (inherited from Mom and Dad) – Type A – Genes are AA or AO – Type B – Genes are BB or BO – Type AB (co-dominant) – Genes are AB • The lack of these antigens is called type O (recessive) – Genes are OO • Antibodies form against the antigens not present in the blood. – Example: Type A blood has RBC’s with the A antigen and Anti-B Antibodies 28 29 30 Rh Blood Groups • Named because of the presence or absence of one of eight Rh antigens • Determines whether the blood type is positive or negative. • Most Americans are Rh+ (RBC’s carry the Rh antigen) • Problems can occur in mixing Rh+ blood into a body with Rh– blood 31 Rh Dangers During Pregnancy • Danger is only when the mother is Rh– and the father is Rh+, and the child inherits the Rh+ factor • The mismatch of an Rh– mother carrying an Rh+ baby can cause problems for the unborn child – The first pregnancy usually proceeds without problems – The immune system is sensitized after the first pregnancy – In a second pregnancy, the mother’s immune system produces antibodies to attack the Rh+ 32 blood (hemolytic disease of the newborn) Blood Typing • Blood samples are mixed with anti-A and anti-B serum • Coagulation or no coagulation leads to determining blood type • Typing for ABO and Rh factors is done in the same manner • Cross matching – testing for agglutination of donor RBCs by the recipient’s serum, and vice versa 33 Blood Typing Universal donor is OUniversal receiver is AB+ Figure34 10.8 35 Developmental Aspects of Blood • Sites of blood cell formation – The fetal liver and spleen are early sites of blood cell formation – Bone marrow takes over hematopoiesis by the seventh month • Fetal hemoglobin differs from hemoglobin produced after birth - it has a greater ability to pick up oxygen • Fetal Hb is broken down & replaced with regular RBC’s • Jaundice results in the inability to beak down the Hbf quickly enough. If untreated can cause brain 36 damage, lights and sunshine is the treatment. Homeostatic Imbalances 37