In summation, we have covered the following sequence of events, which comprise primary hemostasis.
- The process begins with damage to a vessel wall, as blood flows outside the vasculature.
- The body responds with vasoconstriction, decreasing blood flow to the affected area.
- Platelets begin sticking to the damaged vessel walls (platelet adhesion).
- As the platelets stick, they change their shape (platelet activation) and release chemicals which signal other platelets to respond (platelet secretion).
- As other platelets arrive, they begin sticking to one another, clumping together, forming a plug to fill in the breach (platelet aggregation).
- This plug, while strong, is a temporary fix, and must be reinforced with fibrin strands to effectively fill the breach during the vessel repair process (secondary hemostasis).