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Clotting cascade
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Each pathway requires what 4 components?
enzyme
cofactor
calcium
phospholiped surface
The extrinsic pathway begins with tissue factor (TF) and factor VIIa. Where is TF derrived from?
brain
TF is on subendothelial surfaces and in monocytes. It is released by damage to blood vessels or when monocytes are exposed to endotoxin.
What lab test is used to test the extrinsic pathway?
PT
Why is it called the extrinsic pathway?
Because TF has to be added to the pathway
What drug affects the extrinsic pathway? How?
Coumadin, by inhibiting the vitamin K dependent factors
What are the vitamin K dependent factors?
II, VII, IX, X, protein C, protein S
What does a prolonged PT time imply?
factor VII defeciency
liver disease
vitamin K defeciency
aquired inhibitor to factor VII
What lab test examines the intrinsic pathway?
aPTT
What are the steps of the intrinsic pathway?
11 to 11a
which catalyzes 9 to 9a
using cofactor 8, 9a (plus Ca plus Pl) transforms to 10
What drug affects the intrinsic pathway? How?
Heparin, by increasing the anticoagualtion properties of antithrombin 3
What are the steps of the common pathway?
10 to 10a
10a +5a (+Ca+Pl) =2 (prothombin)
2 (prothrombin) to 2a (thrombin)
2a becomes a catalyst for converson of fibrinogen (2) to fibrin (with the help of factor 13)
What do protein C and S inhibit?
5a and 8a
How is plasmin formed?
Starts as plasminogen and is converted to plasmin by TPA (which is released by endothelial cells)
What does plasmin do?
cleaves bond in fibrin and fibrinogen (breaking up the clot)
Author
pollyannapole
ID
20428
Card Set
Clotting cascade
Description
More info than you even wanted on how blood clots
Updated
2010-05-23T20:13:38Z
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