CLINICAL MEDICINE

Detailed explanation-1: -Fibrinogen is a soluble macromolecule, but forms an insoluble clot or gel on conversion to fibrin by the action of the serine protease thrombin, which is activated by a cascade of enzymatic reactions triggered by vessel wall injury, activated blood cells, or a foreign surface (Fig.

Detailed explanation-2: -The coagulation process consists of the conversion of prothrombin to thrombin and of the subsequent action of thrombin on fibrinogen to produce fibrin. In the fibrinogen-fibrin conversion fibrinogen, already a high polymer of many amino acids is converted to an even higher polymeric form or coagulum, the fibrin clot.

Detailed explanation-3: -Activated thrombin leads to cleavage of fibrinogen into fibrin monomers that, upon polymerization, form a fibrin clot. Therefore, activation of prothrombin is crucial in physiological and pathophysiological coagulation.

Detailed explanation-4: -Thrombin directly converts fibrinogen to fibrin, thereby leading to immediate clot formation and “short-circuiting” the upstream mechanism of the coagulation cascade, where heparin and warfarin interact.

Detailed explanation-5: -When tissue damage results in bleeding, fibrinogen is converted at the wound into fibrin by the action of thrombin, a clotting enzyme. Fibrin molecules then combine to form long fibrin threads that entangle platelets, building up a spongy mass that gradually hardens and contracts to form the blood clot.