A blood clot consists of a network of threads called fibrins in which dead and damaged formed elements of blood are trapped. Thrombin converts fibrinogen to fibrin. Thrombokinase is an enzyme complex that converts inactive prothrombin into active thrombin. This complex is formed by a series of linked enzymic reactions (cascade process) involving a number of factors present in the plasma in an inactive state. An injury or a trauma stimulates the platelets in the blood to release certain factors which activate the mechanism of coagulation. Certain factors released by the tissues at the site of injury also can initiate coagulation.