Final answer:
The conversion of prothrombin to thrombin is the critical step in the common pathway of blood clotting, which follows both the intrinsic and extrinsic coagulation pathways.
The critical step in the formation of a blood clot by way of intrinisc pathway is the conversion of_prothrombin
Step-by-step explanation:
The critical step in the formation of a blood clot by way of the intrinsic pathway is the conversion of prothrombin to thrombin. In the common pathway, which both the intrinsic and extrinsic pathways lead to, activated factor X, in the presence of the enzyme prothrombinase, converts prothrombin (factor II) into thrombin. Thrombin then acts on fibrinogen (factor I) to convert it into insoluble fibrin strands, which form the structural basis of a clot. Factor XIII then works to stabilize the fibrin clot. This process is essential to stop bleeding by sealing off the damaged vessel.