The first step in the initiation of primary hemostasis for clot formation?

Steps in hemostasis at the site of injury i) Vasoconstriction • Immediate hemostasis following injury is achieved by brief arteriolar vasoconstriction. It is due to the reflex neurogenic mechanism. This effect is transient. ii) Primary hemostasis • It is achieved by formation of the primary hemostatic plug (platelet plug). Following an injury to endothelium, the thrombogenic subendothelial matrix is exposed and allows the platelets to adhere with collagen of ECM. These platelets are activated and recruit other platelets by their secretions. iii) Secondary hemostasis • Activation of coagulation (clotting) system leads to the formation of the secondary hemostatic plug (definitive plug or fibrin clot) which is composed of fibrin, platelets, RBCs, and thrombin. iv) Dissolution of clot • Activation of the fibrinolytic system results in dissolution of the clot.