13.02.3 Coagulation

Coagulation is very complicated. The process of coagulation indicated in Figure 13.10 is a much simplified version. Coagulation is a cascade of events which involves several factors from the liver, some of which are vitamin K-independent, and some of which (including prothrombin) are vitamin K-dependent. There also tissue and platelet factors, which eventually lead to the conversion of prothrombin to thrombin in the circulation. Factor Xa is the enzyme necessary for breaking down prothrombin to thrombin. In turn, Thrombin is responsible for changing fibrinogen, which is a soluble plasma protein into fibrin, an insoluble protein, which is part of the clot.