MCQ IN MEDICINE

Detailed explanation-1: -On cleavage of fibrinopeptides by thrombin, fibrinogen is converted to fibrin monomers, which interact via knobs exposed by fibrinopeptide removal in the central region, with holes always exposed at the ends of the molecules.

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: -It activates factor XI, thus preventing fibrin clots from undergoing fibrinolysis. Thrombin not only cleaves fibrinogen to fibrin, but also through the activation of factor XIII effects the cross-linking of fibrin monomers to produce a firm fibrin clot.

Detailed explanation-5: -When blood clotting is activated, fibrinogen circulating in the blood is converted to fibrin, which in turn helps to form a stable blood clot at the site of vascular disruption. Coagulation inhibitor proteins help to prevent abnormal coagulation (hypercoagulability) and to resolve clots after they are formed.