Fig.10.2 Fibrinolysis. The fibrinolytic system functions to degrade fibrin, thereby allowing lysis of formed thrombus. The enzyme that cleaves fibrin is termed plasmin, and this is formed from a precursor protein in plasma termed plasminogen. Plasminogen is converted to plasma by the action of plasminogen activators. Other factors, grouped as plasminogen activator inhibitors, antagonize the process of forming plasmin, one such being PAI -1, which interacts with protein C. The end products of the fibrinolytic process are fibrin degradation products. These products also have anticoagulant activity. Plasminogen activators have been considered for therapeutic administration to promote the lysis of thrombus, for example in the immediate management of coronary artery thrombosis.