Fibrinolysis

The final component of normal hemostasis is dissolution of the fibrin mesh, or fibrinolysis. Plasmin breaks down the fibrin clot. Plasmin forms when plasminogen is cleaved by plasminogen activators including tissue plasminogen activator and urokinase. The endothelial cells release tissue plasminogen activator in response to injury and in response to thrombin. Urokinase seems to play a more important role in extravascular fibrinolysis.

The main inhibitors of fibrinolysis are plasminogen activator inhibitor-1, which blocks the effects of tissue plasminogen activator that result in fibrinolysis, and thrombin-activatable fibrinolysis inhibitor, which blocks the conversion of plasminogen to plasmin.³

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