What happens during the coagulation phase?

• A. Immediate platelet aggregation without clotting factors.
• B. Only endothelial repair.
• C. Red blood cell lysis.
• D. Involves a cascade of clotting factors activated to convert fibrinogen to fibrin by thrombin, forming a mesh that stabilizes the platelet plug.

Answer: (D)

During coagulation, the clotting factors are activated in a cascade that ends with thrombin producing fibrin from fibrinogen. The resulting fibrin mesh stabilizes the platelet plug, creating a sturdy clot and completing secondary hemostasis. This step solidifies the initial platelet plug formed earlier and is distinct from endothelial repair or any red blood cell lysis.