<P> 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 Willebrand factor which initiate the maintenance of hemostasis after injury . Hemostasis has three major steps : 1 ) vasoconstriction , 2 ) temporary blockage of a break by a platelet plug , and 3 ) blood coagulation , or formation of a fibrin clot . These processes seal the hole until tissues are repaired . </P>
describe the three phases of the normal blood clotting process
vasoconstriction , temporary blockage of a break by a platelet plug blood coagulation