(4) Platelets Explanation: Coagulation is the process by which blood forms clots. It is an important part of hemostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrincontaining clot to stop bleeding and begin repair of the damaged vessel. Disorders of coagulation can lead to an increased risk of bleeding (hemorrhage) or obstructive clotting (thrombosis). Coagulation begins almost instantly after an injury to the blood vessel has damaged the endothelium lining the vessel.