What is the mechanism of the fibrinolytic system?

The fibrinolytic system is a physiological reaction that is invoked at the final stage of the hemostatic mechanism. It decomposes fibrin, the end product of the coagulation system, which is therefore called “fibrinolytic system”. There is plasminogen in the plasma, and it is converted to the active enzyme plasmin as often as required. Plasmin is a strong protease which effectively decomposes fibrin in blood. Plasminogen is activated by serine protease called plasminogen activator (PA). There are two types of plasminogen activator in the living body : urokinase PA (u-PA or UK) and tissue PA (t-PA). On the other hand, alpha 2 plasmin inhibitor (α 2-PI) and PA inhibitor (PAI) inhibit activation of plasmin and PA, respectively thus controlling activation of the fibrinolytic system.