Vascular Disorders and Thrombosis II Flashcards
what are the major players in hemostasis?
endothelium and underlying matrix
platelets
circulating factors
what do prostacyclin and nitric oxide do with thrombosis?
inhibit platelet activation, adhesion, and aggregation
vasodilate
does ADPase promote thrombosis or prevent it?
prevents it: degrades pro-thrombotic ADP
what does tissue plasminogen activator do?
activates plasmin to digest fibrin
what are the membrane associated factors of endothelium that prevent thrombus?
thrombomodulin and circulating proteins C and S
heparin-like molecules and circulating antithrombin III
tissue factor pathway inhibitor
what does endothelin do?
vasoconstricts
what does von Willebrand Factor do?
enhances platelet binding to collagen
what does platelet activating factor do?
recruits and activates platelets
what does tissue factor (factor III) do?
initiates extrinsic coagulation pathway
what do plasminogen activator inhibitors do?
inhibit fibrinolysis
what do platelets secrete to promote aggregation?
calcium
ADP- also activation
thromboxane A2- vasoconstricts as well
what is the primary producer of most circulating clotting and anticoagulant factors?
liver
what clotting factors produced by the liver are vitamin K-dependent?
II, VII, IX, X
protein C and protein S
what is the primary initiator of the coagulation cascade in vivo?
extrinsic pathway: activated by exposure of Tissue Factor (factor III) to factor VII in circulation
what is the primary amplifier of the coagulation cascade in vivo?
intrinsic pathway: activated by negatively-charged substances, collagen, inflammatory pathways
what factors are involved in the intrinsic pathway for the coagulation cascade?
factors XII, XI, IX, VIII
when do the extrinsic and intrinsic pathways merge?
activation of factor X: factor X and V= prothrombinase complex
what is the ratio of blood to anticoagulant for a coagulation test?
9:1
what is the initiation of the cell-based model of coagulation?
circulating VIIa binds tissue factor on surface damaged endothelial cells
factor Xa and a small amount of thrombin are produced
how does thrombin amplify coagulation?
activates platelets, cleaves von Willebrand’s Factor-VIII complex, and activates factors V, VIII, XI