Mechanism of Blood Coagulation Intrinsic pathway Extrinsic pathway Collagen or other Damage exposes activators tissue factor(Ill) Active XII Tissue factor Ca2+ (Ill)and XI Active active Vll XI positive feedback Ca2+ Active X VIn Ca2+,PL X Active X Common pathway Ca2+,V,PL ---------positive feedback------------ Thrombin Prothrombin PL=phospholipids Fibrinogen Fibrin XI Active XIll Cross-linked fibrinMechanism of Blood Coagulation Mechanism of Blood Coagulation