Chapter 17: Blood

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tad.ramage
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270914
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Chapter 17: Blood
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2014-05-07 15:34:56
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blood
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Anatomy and Physiology
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blood
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  1. Blood
    Fluid connective tissue
  2. Spun tube of blood yields three layers
    • Plasma on top (55%)
    • WBCs and platelets in buffy coat (<1%)
    • Erythrocytes on bottom (45%)
  3. Hematocrit
    • Percent of blood volume that Erythrocytes (RBCs)
    • 42-52% for males
    • 37-47% for females
  4. Physical Characteristics and Volume
    • Sticky, opaque fluid with metallica taste
    • Color: high O2 - scarlet / low O2 - dark red
    • pH: 7.35-7.45
    • 8% of body weight
    • Average volume: 5-6 L males / 4-5 L females
  5. Functions of Blood
    • Distribution
    • Regulating blood levels of substances
    • Protection (antibodies - WBCs)
  6. Distribution Functions
    • Maintaining body tempt by absorbing and distributing heat (warm - dilate / cold - constrict)
    • Maintain normal pH using buffers
    • Maintaining adequate fluid volume in circulatory system
  7. Protection Functions
    • Preventing blood loss - plasma proteins and platelets initiate clot formation
    • Preventing infection - antibodies, compliment proteins, WBCs
  8. Blood Plasma
    90% water with over 100 dissolved solutes - nutrients, gases, hormones, wastes, inorganic ions
  9. Formed Elements
    • Only WBCs are complete cells
    • RBCs have no nuclei or other organelles
    • Platelets are cell fragments
    • Most formed elements survive in bloodstream only few days (with the exception of Erythrocytes)
    • Most blood cells originate in bone marrow and do not divide
  10. Erythrocytes
    • biconcave discs, anucleate
    • Diameters larger than some capillaries
    • Major factor contributing to blood viscosity
    • Filled with hemoglobin (hb) for gas transport
  11. Viscous
    having a thick, sticky consistency between solid and liquid
  12. Erythrocytes - Gas Transport
    Hemoglobin binds reversibly with oxygen
  13. Hemoglobin Structure
    • Globin: composed of 4 polypeptide chains
    • Heme: pigment bonded to each globin chain (contains iron)
    • Each Hb molecule can transport 4 O2 (each Iron atom carries one O2 molecule)
    • Each RBC contains 250 million Hb molecules
  14. Hemoglobin (Hb)
    • O2 loading in lungs - produces oxyhemoglobin (ruby red)
    • O2 unloading in tissues - produces deoxyhemoglobin or reduced hemoglobin (dark red)
    • O2 loading in tissues - 20% of CO2 in blood binds to Hb (carbaminohemoglobin)
  15. Hematopoiesis
    Blood cell formation in red bone marrow (in axial skeleton, girdles, and proximal epiphyses of humerus and femur)
  16. Hematopoietic Stem Cells
    • Hemocytoblasts
    • Give rise to all formed elements
    • Hormones and growth factors push cell toward specific pathway of blood cell development
  17. Regulation of Erythropoiesis
    • Too few RBCs leads to tissue hypoxia
    • Too many RBCs increases blood viscosity
    • Balance between RBC production and destruction depends on (hormonal controls - adequate supplies of iron, amino acids, and B vitamins
  18. Regulating Erythropoiesis
    • 1. Hypoxia: body is deprived of adequate oxygen supply
    • 2. Kidney releases erythropoietin
    • 3. Erythropoietin stimulates red bone marrow
    • 4. Enhances erythropoiesis increases RBC count
    • 5. O2- carrying ability of blood rises
  19. Fate and Destruction of Erythrocytes
    • Life span: 100-120 days
    • Old RBCs become fragile; Hb begins to degenerate
    • Get trapped in smaller circulatory channels especially in spleen
    • Macrophages engulf dying RBCs in spleen
  20. Anemia
    • Abnormally low O2-carrying capacity
    • Blood O2 levels cannot support normal metabolism
    • Accompanied by fatigue, pallor, shortness of breath, chills
  21. Causes of Anemia
    • Blood Loss
    • Low RBC Production
    • High RBC Destruction
  22. Hemorrhagic anemia (blood loss)
    • Causes: rapid blood loss
    • Treatment: blood replacement
  23. Chronic hemorrhagic anemia (blood loss)
    Cause: slight but persistent blood loss
  24. Iron-deficiency anemia (low RBC production)
    • Cause: hemorrhagic anemia, low intake or impaired absorption
    • Treatment: iron supplements
  25. Renal Anemia (low RBC production)
    • Cause: Lack of Erythropoietin
    • Treatment: synthetic erythropoietin
    • often accompanies renal disease
  26. Pernicious anemia (low RBC production)
    • Cause: Autoimmune disease - Lack of intrinsic factor needed to absorb B12 (deficiency of vitamin B12)
    • Treatment: B12 injections or nasal gel
    • also caused by low dietary B12 (vegetarians)
  27. Hemolytic anemia (high RBC destruction)
    Cause: Hb abnormalties - incompatible transfusions - infections
  28. Sick-cell Anemia
    • Cause: Hemoglobin S - one amino acid wrong in a globin beta chain
    • RBCs crescent shaped when unload O2 or blood O2 low
    • Poor O2 delivery - pain
  29. Leukocytes
    • Make up of less than 1% of total blood volume
    • Function in defense against disease (can leave capillaries)
  30. Leukocytosis
    • WBC count over 11,000 cells per nanoliter
    • normal response to infection
  31. Two Categories of Leukocytes
    • Granulocytes
    • Agranulocytes
  32. Granulocytes (Leukocyte)
    • Visible cytoplasmic granules
    • Neutrophils, Esoinophils, Basophils
  33. Agranulocytes (Leukocyte)
    • No visible cytoplasmic granules - spherical or kidney-shaped nuclei
    • Lymphocytes, Monocytes
  34. Neutrophils (Granulocytes)
    • Most numerous WBCs
    • Structure: 3-6 lobes in nucleus; twice size of RBCs - granules stain lilac; contain hydrolytic enzymes or defensins
    • Very phagocytic - "bacteria slayers"
  35. Eosinophils (Granulocytes)
    • Structure: red-staining granules - bilobed nucleus - granules lysosome-like
    • Role in: allergies and asthma - modulating immune response
  36. Basophils (Granulocytes)
    • Rarest WBCs
    • Structure: nucleus deep purple with 1-2 constrictions - large, purplish-black granules contain histamine
    • functionally similar to mast cells
  37. Lymphocytes (Agranulocytes)
    • Second most numerous WBC
    • Structure: large, dark purple, circular nuclei with thin rim of blue cytoplasm
    • Located in: mostly in lymphoid tissue - few circulate in blood
    • Crucial to immunity
  38. Monocytes (Agranulocytes)
    • Largest leukocytes
    • Structure: abundant pale-blue cytoplasm - dark purple-staining, U- or kidney-shaped nuclei
    • Actively phagocytic cells (crucial against, viruses, intracellular acterial parasites, and chronic infections)
    • Activate lymphocytes to mount an immune response
  39. Lymphoid Stem Cells
    form lymphocytes
  40. Myeloid Stem Cell
    Forms Monocytes, Neurophils, Eosinophils, Basophils
  41. Leukopenia
    Abnormally low WBC count - drug induced
  42. Leukemia
    • Cancer - overproduction of abnormal WBCs
    • Named according to abnormal WBC clone involved
    • Cancerous leukocytes fill red bone marrow
    • Immature nonfunctional WBCs in bloodstream
    • Death usually from internal hemorrhage; overwhelming infections
    • Myeloid leukemia: involves myeloblast descendants
    • Lymphocytic leukemia: involves lymphocytes
  43. Infectious Mononucleosis
    • Highly contagious viral disease - Epstein-Barr virus
    • High numbers atypical agranulocytes
    • Symptoms - tired, ach, chronic sore throat, low fever
    • Runs course with rest
  44. Platelets
    • Cytoplasmic fragments of megakaryocytes
    • Blue-staining outer region; purple granules
    • Normal = 150,000-400,000 platelets /mL of blood
    • Form temporary platelet plug that helps seal breaks in blood vessels
  45. Formation of platelets
    Hematopoietic stem cell - megakaryoblast - megakaryocyte - platelets
  46. Hemostasis
    • Fast series of reactions for stoppage of bleeding
    • Requires clotting factors, substances released by platelets and injured tissues
  47. Steps of hemostasis
    • 1. Vascular spasm - smooth muscle contracts
    • 2. Platelet plug formation - injury to lining of vessel exposes collagen fibers; platelets adhere - platelets release chemicals that make nearby platelets sticky; platelet plug forms
    • 3. Coagulation - fibrin forms a mesh that traps red blod cells and platelets, forming the clot

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