Flashcards in PATH: Hemostasis and Thrombosis Deck (22):
What is the function of hemostasis?
To maintain blood in the vascular system fluid and free of clots , yet allow rapid activation of clotting if necessary
What is thrombosis?
A pathologic extension of hemostasis in which there is inappropriate activation of the hemostatic system
What are the anti-thrombotic properties of endothelium?
Anti-platelet effects (barrier function, ADP breakdown, NO, prostacyclin), anti-coagulant properties, and fibrinolytic properties (t-PA)
What are the pro-thrombotic properties of endothelium?
Synthesis of von Willebrand Factor, procoagulant (synthesize tissue fator activating extrinsic coag. pathway, and expresses binding sites for activated clotting factors IX and X), and anti-fibrolytic (PAI)
What kind of granules do platelets contain?
Alpha granules and electron dense bodies
What are 3 functions of activated platelets in hemostasis?
Adhesion to ECM (vWF), secretion/ release, aggreagation causing generation of ADP, thrombin and TXA2
What occurs during primary hemostasis?
Vasoconstriction, exposure of blood elements to collagen, release of tissue factors that activate coagulation cascade and formation of a hemostatic plug at the SOI
What is the effect of TXA2?
Causes vasoconstriction which lowers blood flow to the area allowing more platelets to filter out and become attracted to other platelets. This allows for the formation of the primary hemostatic plug
How do platelets bind to vWF?
How are platelets bound to one another in a hemostatic plug?
Connected through fibrinogen
What converts Fibrinogen to fibrin and what effect does this have?
Thrombin converts fibrinogen to fibrin which is a much stronger molecule
What are the effects of thrombin in generating hemostasis?
Increase neutrophil adhesion, activate monocytes, lymphocytes, and endothelium, converts fibrinogen to fibrin and increases platelet aggregation and stimulation which causes thromboxane A2 release
What are the initiators of the intrinsic and extrinsic coagulation pathways?
Extrinsic by tissue factor and intrinsic by Factor XII or Hageman Factor
What is the ultimate goal of the coagulation pathways?
Activation of Factor II to IIa (thrombin)
What products are released by the endothelium that block the coagulation cascade?
Thrombomodulin and t-PA
How does plasmin act?
Acts on fibrin to make fibrin degradation products
What is a thrombus?
A solid mass or plug formed from blood elements found at the site of formation
What is an embolus?
Detached intravascular solid, liquid, or gaseous mass found at a site different from its origin
What is Virchow's Triad?
The three major factors that favor thrombosis: vascular lesions (endothelial injury), decreased flow (stasis), and hypercoagulability
What is the cellular driver and mediator of arterial thrombosis? Venous? Which is more common?
Arterial- platelet driven/mediated; Venous- RBC; Arterial more common
What is activated protein C resistance?
Factor V deficiency where heterozygotes are 3-10 times more likely to develop thromboses, and homozygotes have a 50 fold increased risk