Coagulation cascade
NB. Before coagulation can occur, Virchow's triad must be present. Circulatory stasis, endothelial injury, hypercoagulable state.There are 2 pathways in the coagulative cascade:
(1) Extrinsic (measured by the pro-thrombin time)
Clotting factors involved are 10, 5, 2, 1 and 7. 7 is the only factor unique to the extrinsic pathway.
(2) Intrinsic (measured by activated partial thromboplastin time)
Clotting factors involved are 10, 5, 2, 1 (which is similar to extrinsic) and 12, 11, 9, 8.
Factors 8 and 9 are implicated in hemophillia A and B respectively.
NB. Vitamin K dependent factors are 10, 9, 7, 2. Which involves both the extrinsic (7) and intrinsic (9) pathways.
NB. factor 1 is fibrinogen, factor 2 is prothrombin.
Wei Qiang converses @ 17:23
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