- See:
-
deep venous thrombosis
-
hypercoagulable states
XII + Surface:
intrinsic path: heparin/ PT
|
XIIa
|
VIIa + TF:
extrinsic path: (
warfarin/PT)
XI---XIa <----/
|
IX-----IXa
|
VIIIa |
|
Thrombomodulin
X----------Xa
--------> Prot. C/S --
/
| Va
|
/
|
|
Antithrombin III ----->
II-------IIa ----------------------> VIIIa & Va
|
|
Fibrinogen----Fibrin
- Specific Factors:
-
fibrinogen (factor I);
- prothrombin (factor II)
- converts finbrinogen to fibrin
- activates V, VIII & XIII (when bound to thrombomodulin)
- activates protein C;
-
Vit K dependent;
- factor V:
when activated, serves as enzyme co-factor
- factor Xa: part of Xa/Va complex which activates prothrombin;
- factor VII:
- part of factor VII/tissue factor complex that activates factor X and IX;
- is activated by Xa;
-
Vit K dependent;
- factor VIII: serves as enzyme cofactor to help activate factor X;
- factor IX:
- acts w/ IXa/VIIIa/phos complex that activates factor X;
-
Vit K dependent;
- factor X:
- acts as Xa/Va phos complex that actives prothrombin;
-
Vit K dependent;
- factor XII:
- protein C:
- when activated to Ca by thrombin bound to thrombomodulin, inhibits by proteolysis factors VIIIa and Va in reactions requiring prot S
and phospholipids as cofactors;
Vit K dependent;
- antithrombin III:
- is a plasma protease inhibitor that serves as a protease scavenger;
- any of the blood-clotting enzymes that move away from the growing clot rapidly form a complex, and their activities are neutralized
- formation of complexes is accelerated by
heparin, forms of which are located in the microvasculature on the surfaces of endothelial cells;
- inhibitor of the enzymes thrombin, Xa, IXa; Is activated by
heparin;
Medical Progress: The Regulation of Hemostasis: The Protein C System.
Deficiencies of coagulation-inhibiting and fibrinolytic proteins in outpatients with deep-vein thrombosis.
Prevention of venous thrombosis after total hip arthroplasty. Antithrombin III and low-dose heparin compared with dextran 40.
The effect of total hip replacement and general surgery on antithrombin III in relation to venous thrombosis.
Review Article: Seminars in Medicine of the Beth Israel Hospital, Boston: Molecular And Cellular Biology Of Blood Coagulation.
