MICROANATOMY

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. 13.1).

Detailed explanation-2: -In the clotting reaction proper, thrombin converts fibrinogen into fibrin and as a result the fibrin molecules aggregate into a network structure, called the clot.

Detailed explanation-3: -In the fluid phase, fibrinogen is converted to fibrin in a reaction catalyzed by thrombin, which releases fibrinopeptides A (FpA) and B (FpB) from the amino-termini of the A and B chains, respectively, and produces fibrin monomers.