answers: endothelial injury
context: Hemostasis Hemostasis or haemostasis is a process which causes bleeding to stop, meaning to keep blood within a damaged blood vessel (the opposite of hemostasis is hemorrhage). It is the first stage of wound healing. This involves coagulation, blood changing from a liquid to a gel. Intact blood vessels are central to moderating blood's tendency to form clots. The endothelial cells of intact vessels prevent blood clotting with a heparin-like molecule and thrombomodulin and prevent platelet aggregation with nitric oxide and prostacyclin. When endothelial injury occurs, the endothelial cells stop secretion of coagulation and aggregation inhibitors and instead secrete von </s> but before the creation of the fibrin mesh clot, which is the more permanent solution to the injury. The result of the platelet plug formation is the coagulation of blood. It can also be referred to as primary hemostasis. For many years, the critical role that platelets (also known as thrombocytes) played in hemostasis and blood coagulation went unnoticed by scientists. Even though the existence of platelets as a cell fragment was initially discovered in 1882, it took scientists until the 1960s before they moved their interest from the interaction of platelets with blood coagulation to the interaction of platelets </s> and genetic or disease-related deficiencies in the blood's clotting abilities. Platelet activation can occur through different mechanisms such as a vessel wall breach that exposes collagen, or tissue factor encryption. The platelet activation causes a cascade of further platelet activation, eventually causing the formation of the thrombus. This process is regulated through thromboregulation. Blood clot prevention and treatment reduce the risk of stroke, heart attack and pulmonary embolism. Heparin and warfarin are used to inhibit the formation and growth of existing thrombi, with the former used for acute anticoagulation while the latter is used for long-term anticoagulation. The mechanism of
question: the stimulus for the formation of a platelet plug or a blood clot is