Anatomy and Physiology II Practice Test

Thrombin plays a crucial role in the coagulation cascade by converting fibrinogen, an inactive plasma protein, into fibrin. When thrombin cleaves fibrinogen, it transforms this soluble protein into fibrin, which then polymerizes to form a fibrous gel structure. This fibrin mesh is essential for the formation of blood clots, stabilizing the platelet plug and providing a scaffold for tissue repair.

Fibrinogen is specifically designed to be a precursor for fibrin during the hemostatic process, which is critical in preventing excessive bleeding. The other proteins listed, such as albumin and globulin, have different primary functions in the body. Albumin mainly contributes to osmotic pressure and transport of various substances, while globulins serve as antibodies or transport proteins. Prothrombin is a precursor to thrombin, but it does not directly convert into a fibrous gel itself.