Final answer:
When a blood vessel is damaged, clot formation includes the conversion of fibrinogen into fibrin by the action of the enzyme thrombin. This process is called coagulation.
Step-by-step explanation:
When a blood vessel is damaged, clot formation includes the conversion of fibrinogen into fibrin by the action of the enzyme thrombin. This process is a crucial part of the coagulation pathway, specifically the common pathway following the activation of factor X.
Initially, factor X is activated by the intrinsic or extrinsic pathway, leading to the conversion of prothrombin to thrombin by the enzyme prothrombinase. The thrombin then acts on fibrinogen, converting it into the insoluble protein fibrin, which forms a mesh that traps platelets and erythrocytes, ultimately producing a blood clot. As the vessel heals, the process known as fibrinolysis gradually degrades the clot, allowing normal blood flow to be restored.