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Anatomy & Physiology: Blood and Hemostasis

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Terms in this set (25)

  • Primary functions of blood
    Transport of O2, nutrients, wastes, and hormones; Regulation of body temperature, pH, and fluid volume; Protection against blood loss and infection.
  • Composition of blood
    Blood consists of plasma (55%), erythrocytes (45%), and a thin buffy coat of leukocytes and platelets (<1%).
  • Erythrocyte structure
    Biconcave, anucleate cells filled with hemoglobin; flexible due to spectrin protein; optimized for gas transport.
  • Hemoglobin structure and function
    Consists of four polypeptide chains (two alpha, two beta) each with a heme group containing iron that binds O2 reversibly.
  • Erythropoiesis
    Process of RBC formation in red bone marrow, taking about 15 days, regulated by erythropoietin and requiring iron, B12, and folic acid.
  • Regulation of erythropoiesis
    Stimulated by hypoxia via kidney-released erythropoietin; balanced to avoid hypoxia or excessive blood viscosity.
  • Life span and fate of erythrocytes
    Live 100-120 days; old RBCs are phagocytized in spleen; hemoglobin components recycled or excreted as bilirubin.
  • Anemia
    Condition with abnormally low O2-carrying capacity due to blood loss, decreased RBC production, or increased RBC destruction.
  • Polycythemia
    Excess RBCs increasing blood viscosity; caused by bone marrow cancer or secondary to hypoxia; blood doping mimics this.
  • Leukocytes (WBCs) characteristics
    Complete cells with nuclei; defend against disease; can exit bloodstream via diapedesis; two groups: granulocytes and agranulocytes.
  • Granulocytes vs Agranulocytes
    Granulocytes have visible cytoplasmic granules (neutrophils, eosinophils, basophils); agranulocytes lack granules (lymphocytes, monocytes).
  • Leukopoiesis
    WBC production stimulated by interleukins and colony-stimulating factors; originates from hemocytoblast stem cells.
  • Platelets origin and function
    Cytoplasmic fragments of megakaryocytes; contain clotting chemicals; form temporary plugs to seal vessel breaks.
  • Hemostasis steps
    1) Vascular spasm (vasoconstriction), 2) Platelet plug formation, 3) Coagulation (fibrin mesh formation).
  • Platelet plug formation
    Platelets adhere to exposed collagen, release ADP, serotonin, and thromboxane A2, promoting aggregation and vascular spasm.
  • Coagulation pathways
    Intrinsic (clotting factors in blood) and extrinsic (tissue factor outside blood) pathways activate factor X, leading to thrombin formation.
  • Common coagulation pathway
    Thrombin converts fibrinogen to fibrin, forming a mesh that stabilizes the clot; factor XIII cross-links fibrin.
  • Clot retraction and fibrinolysis
    Platelets contract to shrink clot; PDGF and VEGF promote vessel repair; plasmin dissolves clot after healing.
  • Factors limiting clot growth
    Removal/dilution of clotting factors; antithrombin III and heparin inhibit thrombin; endothelial cells secrete anticoagulants.
  • ABO blood group system
    Based on presence of A and/or B antigens on RBCs; plasma contains antibodies against absent antigens; determines compatibility.
  • Rh blood group system
    Presence (Rh+) or absence (Rh−) of D antigen; Rh− individuals form anti-Rh antibodies only after exposure to Rh+ blood.
  • Hemolytic disease of the newborn
    Occurs when Rh− mother sensitized to Rh+ fetus blood produces antibodies that destroy fetal RBCs in subsequent pregnancies.
  • Transfusion reactions
    Mismatched blood causes agglutination, hemolysis, reduced oxygen capacity, and kidney damage; symptoms include fever and chills.
  • Universal donor and recipient blood types
    Type O is universal donor (no A/B antigens); Type AB is universal recipient (no anti-A/B antibodies).
  • Blood typing and cross matching
    Mix donor RBCs with recipient serum and vice versa to detect agglutination; ensures compatibility before transfusion.