Explain why the blood clots and describe the process of events that causes the blood to clot.

If blood vessels are damaged, such as by a cut in the skin, blood clots to perform two functions. 1) to reduce or stop blood loss2) to prevent the entry of pathogens
This triggers a cascade of events, resulting in a blood clot. First, platelets collect and release serotonin, this causes the muscle of the artery to contract, cutting off the blood supply. Thromboplastin then turns prothrombin into thrombin which in turn results in fibrinogen converting into fibrin. Fibrin forms a mesh over the cut, trapping blood cells and forming a blood clot.