Thrombin, after its conversion from prothrombin, catalyzes the conversion of fibrinogen into a fibrin monomer. Additionally, thrombin triggers the conversion of factor XIII into factor XIIIa, which forms covalent bonds that crosslink and stabilize the fibrin monomers.
Finally, thrombin feeds back into the intrinsic and common pathways, accelerating the action of factors XI, V, and VIII.
