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Blood

Blood. Chapter 11 Pgs 343-359. Overview. Functions of Blood Composition of Blood Plasma Plasma proteins Formed Elements Production of formed elements Red blood cells White blood cells Platelets. Functions of Blood.

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Blood

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  1. Blood Chapter 11 Pgs 343-359

  2. Overview • Functions of Blood • Composition of Blood • Plasma • Plasma proteins • Formed Elements • Production of formed elements • Red blood cells • White blood cells • Platelets

  3. Functions of Blood • Transportation of dissolved gases, nutrients, hormones, and metabolic wastes • Regulation of pH and electrolyte composition of ISF • Restriction of fluid loss through damaged vessels and other injury sites • Defense against toxins and pathogens • Stabilization of body temperature

  4. Composition of Blood • Plasma • Formed elements • Red blood cells (RBC) or Erythrocytes • White blood cells (WBC) or Leukocytes • Platelets • Both constitute whole blood • 5-6 L in men • 4-5 L in women

  5. Plasma • Electrolyte concentration similar to ISF • Plasma proteins • Lg so cannot diffuse • 3 primary classes • Albumins • Globulins • Fibrinogen • Serum

  6. Formed Elements: The Production • Hemopoiesis • Embryonic blood cells • Stem cells • Hemocytoblasts

  7. Red Blood Cells (Erythrocytes) • Accounts for 99.9% of formed elements • RBC count (#RBCs per microliter) • Adult male: 5.4million/μl • Hematocrit: % of whole blood occupied by cellular elements • Determined by centrifuge • Adult male: avgs 46% • Closely approx vol of erythrocytes • Hematocrit values often reported as: • Volume of packed red cells (VPRC) • Packed cell volume (PCV)

  8. Structure of RBCs • Specialized to transport oxygen and carbon dioxide • Shape has 2 important effects on function: • Lg SA:vol • Increases rate of diffusion between cytoplasm and plasma • Enables bending and flexing to fit through narrow capillaries • Contains hemoglobin (Hb)

  9. RBC Formation (Erythropoiesis) • Occurs in red bone marrow (myeloid tissue) • Erythroblasts • Very immature RBCs • Actively synthesizing Hb • After 4 days differentiates into: • Reticulocyte • Enter circulation after 2 days in bone marrow • After 24 hrs in circ, complete maturation and become: • Erythrocyte!

  10. RBCs and Blood Types • Blood type classification determined by presence or absence of specific surface antigens in RBC membrane • Surface antigens of RBC called agglutinogens • Genetically determined • 3 important antigens: • A • B • Rh

  11. RBCs and Blood Typing • Type A: antigen A only (40% US pop) • Type B: antigen B only (10%) • Type AB: both A and B (4%) • Type O: neither A nor B (46%) • Rh factor: present in some, absent in others

  12. Divided into 2 groups: Granulocytes Neutrophils Eosinophils Basophils Agranulocytes Monocytes Lymphocytes Microliter typically contains 6,000-9,000 WBCs Most located in connective tissue proper or in organs of lymphatic system White Blood Cells (Leukocytes)

  13. WBC Circulation and Movement • Do not circulate for extended periods of time • 4 characteristics of circulating WBCs: • Amoeboid movement • Diapedesis • Positive chemotaxis • Phagocytosis

  14. WBCs: General Functions • Nonspecific defense • Neutrophils • Eosinophils • Basophils • Monocytes • Specific defense • Lymphocytes

  15. Neutrophils • 50-70% circulating WBCs • Dense, twisted nucleus • 1st to arrive to injury scene • Active phagocytes • Specialize in attacking and digesting bacteria

  16. Eosinophils • 2-4% circulating WBCs • Similar in size to neutrophils • Contain granules and 2-lobed nucleus • Attracted to foreign compounds that have reacted with circulating antibodies

  17. Basophils • Less than 1% circulating WBCs • Numerous granules • Migrate to injury site, cross cap wall, and accum w/in damaged tissue • Discharge granules into ISF • Contain heparin and histamine

  18. Monocytes • 2-8% circulating WBCs • Lg, oval (kidney) shaped nucleus • Remain in circ only 24 hrs before entering tissue • Become a free macrophage • Very aggressive

  19. Lymphocytes • 20-30% circulating WBCs • Lg nucleus w/ thin halo of cytoplasm • Continuously migrating from bloodstream tissues  blood stream • Protect but do not rely on phagocytosis • Attack foreign and abnormal cells

  20. Differential Count and Changes in WBC Profiles • Differential count • Number of circulating WBCs obtained in a blood sample • Values reported indicate the # of each type of cell encountered in a sample of 100 WBCs • Leukopenia • Too few WBCs • Leukocytosis • Too many WBCs • Leukemia • Extreme form of leukocytosis (WBC counts of 100,000/μl

  21. White Blood Cell Formation • Stem cells originate in red bone marrow • All from myeloid stem cells except for lymphocytes • Neutrophils, eosinophils, basophils complete dev in marrow • Monocytes begin in marrow, enter circ, complete development when free macrophages

  22. WBC Formation: Lymphocytes • Lymphoid stem cells migrate from bone marrow to lymphoid tissues • Process called lymphopoiesis • Hormones involved in regulation of WBC populations • Colony-stimulating factors (CSFs) regulate WBCs other than lymphocytes • Thymosins promote differentiation of T-cells from lymphocytes

  23. Platelets • Components of formed elements • Cell fragments; not individual cells • Derived from megakaryocytes • Shed packets of cytoplasm • Platelets! • Initiate clotting process and help close injured blood vessels • Continuously replaced • Thrombocytopenia: abnormally low count • Thrombocytosis: abnormally high count

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