Blood

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Blood

  1. 1. Blood Chapter 18
  2. 2. Blood Composition and Function Components • Blood is the only fluid tissue in the body • Has both cellular and liquid components • Blood cells, or formed elements, are suspended in a nonliving fluid matrix called plasma
  3. 3. What is in a blood sample? • Erythrocytes – red blood cells (about 45% of blood) • Buffy coat – thin, white layer present at erythrocyte-plasma junction • Leukocytes – white blood cells that protect body (less than 1% of blood) • Platelets – cell fragments (less than 1% of blood) • Plasma – fluid portion of blood (remaining 55% of blood)
  4. 4. Physical Characteristics and Volume • Blood is sticky and has a metallic (salty) taste. • Blood is scarlet with large oxygen content and dark red/violet with poor oxygen content. • Blood accounts for 8% of body weight. – Healthy males have 5-6 L – Healthy females have 4-5 L
  5. 5. Blood Functions
  6. 6. Distribution 1. Delivering oxygen from the lungs and nutrients from the digestive tract. 2. Transporting metabolic waste products from cells to elimination sites. 3. Transporting hormones from the endocrine organs to their target organs.
  7. 7. Regulation 1. Maintaining appropriate body temperature. 2. Maintaining normal pH in body tissues. 3. Maintaining adequate fluid volume in the circulatory system.
  8. 8. Protection 1. Preventing blood loss 2. Preventing infection
  9. 9. Blood Plasma • Yellow, sticky fluid • Made mostly from water • Contains over 100 different dissolved solutes • Contains many proteins – Albumin is the protein with greatest volume • Carries certain molecules through circulation • Blood buffer
  10. 10. Blood Plasma (con’t) • Content continuously changes by adding/removing substances • Also distributes heat throughout the body
  11. 11. Formed ElementsElements
  12. 12. 3 Unusual Features of Formed Elements: 1. Only one cell is a true cell (leukocytes) 2. More formed elements only survive for a few days 3. Blood cells do not divide
  13. 13. AKA Red Blood Cells
  14. 14. Red Blood Cells (RBC’s) • Small, flattened discs with depressed centers • Basically, little “bags” or hemoglobin (Hb – the RBC protein that aids in gas transport) • Pick up oxygen in the capillary bed of the lungs and releases it to tissue cells across the capillaries throughout the body. • Transport ~20% of the carbon dioxide by tissue cells back to the lungs.
  15. 15. RBC’s (con’t) • Spectrin, RBC protein, allows the RBC to bend and change shape to move through blood vessels and capillaries. • Women typically have a lower RBC count than men. • Thickness of the blood is affected by the # of RBC’s. (thicker = more RBC’s)
  16. 16. RBC’s (con’t) • Hemoglobin serves as the molecule for gas transport. – 1 hemoglobin molecule can transport 4 oxygen molecules at a time. • Blood cells are made by hematopoiesis in the red blood marrow.
  17. 17. Anemia A condition in which the blood has an abnormally low oxygen- carry capacity. It is not a disease, but a symptom of a disease.
  18. 18. Causes of anemia: 1. An insufficient # of RBC’s • Hemorrhagic anemias result from rapid blood loss. Usually treated with transfusion. • Hemolytic anemias result from RBC’s that rupture prematurely. It is caused by hemoglobin abnormalities, bad blood transfusion, or infection. • Aplastic anemia results from destruction or inhibition of the red marrow by bacterial toxins, drugs, or radiation.
  19. 19. Causes (con’t) 2. Decreased hemoglobin content • Iron-deficiency anemia is generally a secondary result of hemorrhagic anemias, but it can be from an inadequate intake of iron-rich foods. • Athlete’s anemia occurs when athletes exercise vigorously, expanding their blood volume by as much as 15%, diluting the blood. Converts back within a day or so. • Pernicious anemia is caused by a deficiency of vitamin B12, which is provided by meats, poultry and fish.
  20. 20. Causes (con’t) 3. Abnormal hemoglobin • Thalassemias are typically seen in people of the Mediterranean ancestry (Italians and Greeks). RBC’s are thin, delicate, and deficient in hemoglobin. • Sickle-cell anemia is caused by an abnormal hemoglobin molecule which causes the RBC’s to become crescent shaped. The standard treatment is blood transfusion. Occurs chiefly in black people who live in the malaria belt of Africa and among their descendants.
  21. 21. Polycythemia • Abnormal excess of erythrocytes that increase blood thickness • Treated by blood dilution • “Blood Doping” – Artificially induced polycythemia – Practice of drawing off RBC’s and reinserting them later. – Used by athlete’s to increase blood’s oxygen-carrying capacity
  22. 22. AKA White Blood Cells
  23. 23. White Blood Cells (WBC’s) • Only formed element that is a true cell • Critical to our defense system • Protects the body from bacteria, viruses, parasites, toxins, and tumor cells • Slip in and out of capillaries through a process called diapedesis. – WBC’s follow a signal – Go to the area of damage and infection to destroy foreign substances or dead cells
  24. 24. WBC’s (con’t) • When mobilized, body speeds up WBC production, doubling the # in the blood. – When WBC count goes over 11,000 cells per mL, this is called leukocytosis.
  25. 25. Leukocytes are grouped into 2 categories: 1. Granulocytes - Contain specialized membrane-bound cytoplasmic granules 2. Agranulocytes - Lack obvious granules
  26. 26. Granulocytes •Spherical in shape •Phagocytes
  27. 27. Neutrophils • Most numerous of the WBC’s - ~ ½ of the population • Chemically attracted to inflammation • Phagocytize bacteria and fungi • The body’s “bacteria slayers”; numbers increase during bacterial infections
  28. 28. Eosinophils • Filled with digestive enzymes • Lead the attack against parasitic worms • Found in intestinal or respiratory mucosae • Tend to “hang out” where parasitic worms may enter
  29. 29. Basophils • Rarest WBC • Cytoplasm contains histamine- containing granules – Histamine is an inflammatory chemical that acts as a vasodilator and attracts other WBC’s.
  30. 30. Agranulocytes •Lack visible granules
  31. 31. Lymphocytes • 2nd most numerous leukocyte • Large amounts in body; however, small amounts in blood • Found in lymphoid tissue (lymph nodes, spleen, etc.) • T lymphocytes (T cells) act against virus- infected cells and tumor cells. • B lymphocytes (B cells) make plasma cells, producing antibodies that are released into the blood.
  32. 32. Monocytes • Largest leukocytes • Phagocytic and increase in numbers when active • Defend against viruses and parasites
  33. 33. Leukocyte Disorders
  34. 34. Leukemia • Group of cancerous conditions involving blood cells • Without treatment, all are fatal • Immature WBC’s flood into bloodstream • Bone marrow becomes totally occupied by cancerous leukocytes • Because healthy blood cells are crowded out, anemia and bleeding disorders occur.
  35. 35. Leukemia (con’t) • Symptoms include fever, weight loss, and bone pain. • Most common causes of death are internal bleeding and infections. • Treatments include radiation and antileukemic drugs to destroy cancer cells. • Bone marrow transplants are used in selected patients.
  36. 36. Mononucleosis • Called the “kissing disease” • Highly contagious viral disease seen in children and young adults • Caused by the Epstein-Barr virus • Symptoms include feeling tired and achy, sore throat, and a low-grade fever. • No cure  must run its course!!
  37. 37. Platelets Are not cells, only fragments, sometimes called thrombocytes.
  38. 38. Platelets • Essential for clotting when blood vessels are injured • Stick to the damaged site, forming a temporary plug to seal break • Quickly degenerate because they have no nucleus
  39. 39. Hemostasis • Stopping of bleeding • “Plug the Hole” defensive reaction • Three main phases…
  40. 40. Phases of Hemostasis 1. Vascular Spasms • Immediate response  constrict blood vessel • Chemicals released cause vasoconstriction 2. Platelet Plug Formation • Temporary plug formed to seal break • Positive feedback mechanism increases the numbers of platelets to the site to build the plug 3. Coagulation • Blood turns from liquid to gel • Multistep process that requires 30 different substances
  41. 41. Bleeding Disorders Anything that interferes with the clotting mechanism can result in abnormal bleeding.
  42. 42. Thrombocytopenia • A condition in which the # platelets is deficient • Causes spontaneous bleeding from blood vessels all over the body • Even normal movement can cause hemorrhages (petechiae = small purple blotches) • Arises from any condition that suppresses or destroys the bone marrow • Blood transfusions give temporary relief
  43. 43. Impaired Liver Function • Several different hereditary bleeding disorders • Sex-linked genetic disorder • Primarily in males • Lack clotting mechanisms in the blood • Causes prolonged bleeding with even minor cuts • Must receive transfusion or injections of clotting factors.
  44. 44. Transfusions of Whole Blood • The human cardiovascular system is designed to minimize the effects of blood loss by: 1. reducing the volume of affected blood vessels, which helps to maintain normal circulation, and 2. stepping up the production of RBC’s.
  45. 45. Transfusions (con’t) • A loss of 15-30% of blood causes pallor and weakness • More than 30% results in severe shock, which can be fatal • Whole blood transfusions are routine when blood loss is substantial.
  46. 46. Human Blood Groups • People have different blood types and transfusion of incompatible blood can be fatal. • RBC’s membranes have specific antigens on their external surfaces. • One person’s RBC proteins may be recognized as foreign if transfused into someone with a different RBC types • The presence or absence of antigens allows a person’s blood cells to be classified in several blood types.
  47. 47. ABO Blood Groups • ABO blood groups are based on the presence or absence of two agglutinogens, type A and type B • Depending on a person’s inheritance, his or her ABO blood group will be one of the following: – A – B – AB – O
  48. 48. Blood Groups (con’t) • The O blood group, which had neither agglutinogens, is most common. • AB is the least prevalent of the blood types. • Presence of either the A or the B agglutinogen results in group A or B, respectively.
  49. 49. Rh Blood Groups • There are at least 8 different types of Rh agglutinogens, called an Rh factor. • Most people are Rh+, RBC’s carry the Rh antigen. • If a person receives Rh+ blood, the immune system becomes sensitized and begins producing anti-Rh antibodies against the foreign antigen soon after the transfusion. • No problems (hemolysis) occurs the 1st time. • 2nd time, however, and every time thereafter will result in attack and rupture of the donor RBC’s.
  50. 50. Rh (con’t) • An important problem related to the Rh factor occurs in pregnant Rh- women who are carrying Rh+ babies. • 1st pregnancy will be successful, and will result in a healthy baby. • 2nd pregnancy will result in hemolytic disease of the newborn. The mother’s anti-Rh antibodies built up from the 1st pregnancy will attack the baby’s RBC’s. • RhoGAM, a serum containing anti-Rh agglutinins, is administered.

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