Normal hemostasis and coagulation 2. platelet: (1) adhesion to subendothelial connective tissue by Gpib、WF (2) aggregation formation of platelet thrombus by GPib/Ⅲa (3) release phosphatide-Arachidonic Acid -TXA2 further platelet activation and adhesion vIOlent vessel spasmNormal hemostasis and coagulation 2. platelet： （1）adhesion： to subendothelial connective tissue by GPⅠb、vWF （2）aggregation ： formation of platelet thrombus by GPⅡb/Ⅲa （3）release： phosphatide-Arachidonic Acid -TXA2 further platelet activation and adhesion violent vessel spasm