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2011-04-04 00:47:14
SFOS Coagulation Hemostasis

Show Answers:

  1. Define hemostasis
    ID 3 parts of hemostasis triangle
    • The balance between clotting and bleeding
    • Platelet aggregation, blood vessel wall, blood coagulation
  2. 4 steps floowing loss of vascular integrity
    • Vascular contriction
    • Platelet activation
    • Formation of fibrin clot
    • Clot lysis/would healing
  3. What secretes Thromboxane?
    What is its role?
    • Platelets secrete TXA2
    • Activates additional platelets
  4. What is the role of fibrinogen?
    stimulates platelet clumping
  5. Define:
    1. White thrombus
    2. Red thrombus
    • 1. platelet plug of only platelets
    • 2. plug also includes RBCs
  6. What is the role of fibrin?
    Forms clot/mesh to stabilize platelet plug
  7. What is the role of plasmin?
    Dissolution of the clot
  8. What is the role of thrombopoietin?
    • Stimulates maturation of megakaryocytes
    • Produced when platelet levels drop
  9. Name and describe the 3 granules of a platelet
    • Dense granules - contain serotonin (vasoconstrictor), Ca, ADP, ATP
    • Alpha granules - contain fibrinogen, vWF and growth factors
    • Lambda granules - lysosomes
  10. How are platelet granule contents released?
    Granules fuse with Canaliculi (channels) in platelet membrane
  11. What mediates adhesion of platelets to exposed collagen?
    • vWF (von Willebrand factor)
    • bridges glycoprotein of platelet to collagen
  12. What is the end result of platelet signal transduction?
    • G-protein CRs initiate cascade that increases Ca in cell, stimulating Phospholipase A2 (PLA2) release
    • Stimulates increase TXA2 release
  13. Which stimulates/inhibits platelet activity:
    • Thromboxane - stimulates (from platelet)
    • Prostaglandin - inhibits (from vessel wall)
  14. Define the instrinsic coagulation pathway, ID its factors, and its goal
    • Formation of clot without tissue injury (all components in plamsa)
    • XII, XI, IX, VIII, X
    • X --> Xa converts prothrombin to thrombin, which converts fibrinogen to fibrin
  15. Define the extrinsic coagulation pathway, ID its factors and its goal
    • Clot formation in response to tissue injury
    • Tissue factor, VII, X
    • X --> Xa converts prothrombin to thrombin, which converts fibrinogen to fibrin
  16. What inhibits the extrinsic pathway?
    Tissue Factor Inhibitor
  17. Describe thrombin negative feedback
    • Thrombin combines with thrombomodulin
    • Converts C to Ca, which degrades factors Va and VIIIa
  18. Describe dissolution of fibrin clots
    • Plasminogen converted to plasmin by Tissue plasminogen activator and urokinase
    • Digests fibrin
  19. Hemophilia A:
    a. cause
    b. treament
    • a. deficiency in factor VIII
    • b. infusion of factor VIII
  20. Hemophilia B:
    a. cause
    b. treatment
    • a. deficiency in factor IX
    • b. infusion of factor IX
  21. Describe the cause of fibrinogen disorders
    • deficiencies of factor XIII
    • no cross-linking of fibrin
  22. What is von Willebrand Disease?
    • Inherited deficiency in vWF
    • Defective platelet adhesion
  23. How does heparin act as an anticoagulant?
    Activates antithrombin III, which inhibits proteases of the coagulation cascade
  24. How does coumadin act as an anticoagulant?
    • Inhibits vit k dependent reactions in thrombin function
    • Delayed maximum effect (days)
  25. What is the function of aspirin and its mechanism?
    • Inhibitor of platelet activation
    • Reduces TXA2 production