In coagulation, Factor I corresponds to which substance?

In coagulation, Factor I corresponds to which substance?

• A. Prothrombin
• B. Fibrinogen
• C. Fibrin
• D. Platelet factor

Answer: (B)

Fibrinogen is Factor I in the coagulation system. It’s a soluble plasma glycoprotein produced by the liver that circulates in blood. Thrombin, derived from prothrombin (Factor II), cleaves fibrinogen to form fibrin monomers. These monomers then polymerize into a fibrin mesh that stabilizes the clot, with cross-linking added by Factor XIII. Fibrin is the insoluble product of this process, not the initial substrate, and prothrombin is the precursor enzyme that becomes thrombin. Platelet factor refers to a phospholipid surface from platelets that supports clotting but isn’t Factor I.

Fibrinogen is Factor I in the coagulation system. It’s a soluble plasma glycoprotein produced by the liver that circulates in blood. Thrombin, derived from prothrombin (Factor II), cleaves fibrinogen to form fibrin monomers. These monomers then polymerize into a fibrin mesh that stabilizes the clot, with cross-linking added by Factor XIII. Fibrin is the insoluble product of this process, not the initial substrate, and prothrombin is the precursor enzyme that becomes thrombin. Platelet factor refers to a phospholipid surface from platelets that supports clotting but isn’t Factor I.