The coagulation pathway is a cascade of enzymatic conversions, each activating the next enzyme (factor) in the sequence. The final enzyme in this pathway is thrombin (factor IIa) which catalyzes the conversion of fibrinogen to fibrin strands. A series of events must take place involving many reactions and feedback mechanisms before the clot is formed. By means of the extrinsic pathway or intrinsic pathway, or both, leading to a common pathway, the various factors and other reactants respond normally in an orderly, controlled process—the coagulation cascade.
