Category: catabolism
Inverse of coagulation. Plasminogen is the inactive zymogen, activated by tPA (endothelial, fibrin-targeted) or uPA (urokinase, broader). Plasmin cleaves fibrin → fibrin degradation products (D-dimer being the diagnostic marker). PAI-1 inhibits tPA/uPA; α2-antiplasmin inhibits free plasmin. Therapeutic thrombolysis (alteplase, tenecteplase, reteplase) for STEMI + acute ischemic stroke + massive PE works at the tPA step. Tranexamic acid (TXA) is the prototype antifibrinolytic — inhibits plasminogen lysine-binding to fibrin, blocking plasmin generation — used to reduce surgical/trauma/obstetric bleeding.