280b hemostasis Flashcards

1
Q

1st step in hemostasis following vessel injury?

A

neural vasoconstriction

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2
Q

what doe endothelial cell release following injury? what is in it?

A

Weibel-palade bodies

endothelin - vasoconstriction
selectins - rolling of platelets and WBCs
vWF - binds GpIb on platelets

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3
Q

what do WBCs release after they start rolling on endothelium due to selectins?

A

microparticles put tissue factor on surface –> bind platelets and activate

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4
Q

how are the extrinsic and intrinsic pathways connected?

A

TF-VIIIa activate intrinsic

extrinsic (TF-VIIa and Xa) –> small amount of X –> small amount of thrombin –> activates intrinsic pathway

intrinsic is required to form clot b/c extrensic only gets the process started

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5
Q

where does coagulation cascade occur?

A

surface of cells - WBCs rolling along have TF; platelets have other factors on surface

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6
Q

test for clotting? what is added? what is test tubes and blood bags to stop clotting?

A

intrinsic - PTT (partial thromboplastin time) - add silicates/PL

extrinsic - PT (prothrombin time) - add TF

citrate binds Ca

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7
Q

vitamin K - fxn

A

reduced form (vit K epoxide I– warfarin) –> coenzyme for g-carboxylation of II, VII, IX, X, C, S, Z

allows Ca bridge to form b/w negative membrane PL (phosphatidylserine on platelets and macrophages)

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8
Q

Fibrin and FXIII

A

fibrinogen - triple helix of peptides – dimer with disulfide bonded

thrombin cuts off fibrinopeptides A and B –> leave knobs that allow proper fitting b/w dimers to form a half-staggered sequence –> long aggregated polymer

cross linking via FXIII –> forms bond b/w dimers, activated by thrombin

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9
Q

limiting factors for blood coagulation?

A

prothrombin

F V

F VIII

Ca –> must give with blood transfusions b/c citrate is in bad which blocks Ca action –> too low of Ca to form clot

Fibrinogen

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10
Q

what does intact endothelium releases that inhibits platelet aggregation? cleaves vWF? binds thrombin?

A

NO
PGI2
CD66 (ectoADPase)

ADAMSt13 –> vWF

Thrombomodulin –> binds thrombin

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