Removal of a Blood Clot

Plasmin is soluble but it remains active in the location of a clot. As it diffuses into the blood with clot fragments, the plasmin binds to a2-antiplasmin, a serine protease inhibitor (see next section). In addition to inhibiting plasmin in the blood (Fig. 11.10b), a2-antiplas-min inhibits various other serine proteases, especially activated protein C (APC) (next section) and elastase (Sect. 6.2.1). Plasmin action is inhibited where fibrin is cross-linked to fibronectin, but the large fibrin fragments tend to promote healing. The fragments of fibrin are named as shown in Fig. 11.10c and d. Factors that activate or inhibit fibrinolysis are summarized in Table 11.2. 

Major fibrinolysis initiators Major fibrinolysis inhibitors 

Plasminogen/plasmin Tissue plasminogen activator (tPA)/urokinase a2-Antiplasmin Thrombin-activatable fibrinolysis inhibitor 

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The formation, limitation, strengthening, and removal of a blood clot is an integrated biological system, and problems with single components can cause the system to fail. The lack of some blood clotting... 

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