Factor II is also known as what?

Factor II is also known as what?

• A. Fibrinogen
• B. Prothrombin
• C. Thromboplastin
• D. Factor XIII

Answer: (B)

Factor II is the coagulation factor that serves as the precursor to thrombin. It is activated in the common pathway by the prothrombinase complex (Factor Xa with Factor Va on a phospholipid surface in the presence of calcium). This conversion to thrombin is the key step that begins the conversion of fibrinogen to fibrin, forming a stable clot. Prothrombin is a vitamin K–dependent protein produced by the liver; when its activation is impaired, thrombin generation drops and clotting times lengthen. Fibrinogen is actually Factor I, the substrate that thrombin acts on to form fibrin. Thromboplastin refers to tissue factor, which helps initiate the extrinsic pathway rather than being a coagulation factor itself. Factor XIII is the crosslinking enzyme that stabilizes the formed fibrin network, not the inactive precursor to thrombin.

Factor II is the coagulation factor that serves as the precursor to thrombin. It is activated in the common pathway by the prothrombinase complex (Factor Xa with Factor Va on a phospholipid surface in the presence of calcium). This conversion to thrombin is the key step that begins the conversion of fibrinogen to fibrin, forming a stable clot. Prothrombin is a vitamin K–dependent protein produced by the liver; when its activation is impaired, thrombin generation drops and clotting times lengthen.

Fibrinogen is actually Factor I, the substrate that thrombin acts on to form fibrin. Thromboplastin refers to tissue factor, which helps initiate the extrinsic pathway rather than being a coagulation factor itself. Factor XIII is the crosslinking enzyme that stabilizes the formed fibrin network, not the inactive precursor to thrombin.