What prevents the body from losing blood?

The body has several mechanisms to prevent blood loss, primarily through the clotting process. When a blood vessel is injured, platelets rapidly adhere to the site and release chemicals that attract more platelets, forming a temporary plug. Additionally, clotting factors in the blood activate a cascade of reactions that lead to the formation of a stable fibrin clot. Blood vessel constriction also occurs to reduce blood flow to the area, minimizing loss.