Coagulation, or clot formation, involves a meshwork of fibrin threads (thick irregular scribble) in which blood cells become trapped (not shown). This clot stops the loss of blood. It is common to both the intrinsic (top illustration) and extrinsic (lower illustration) pathways of prothrombin activator formation.
Prothrombin and fibrinogen are the last two coagulation factors that need to be activated--although they are not symbolized as hexagons here. Prothrombin activator (encircled in red) enzymatically converts prothrombin to thrombin. This enzymatic action is illustrated by the thick arrow passing through prothrombin activator. Thrombin is the enzyme ...notice thick arrow...that converts fibrinogen to its active form fibrin.
Prothrombin activator (encircled in red) in both illustrations is the same. The same symbolism (yellow complex) for tissue factor and platelet factor emphasizes that there is little difference in these two compounds.
Last update: 4:13 PM 12/8/2003