Activated platelets express negative phospholipids on the exterior leaflet of their cell membrane, release vasoactive compounds, release cytokines, and release growth factors.
When an injury causes a blood vessel wall to break, platelets are activated. They change shape from round to spiny, stick to the broken vessel wall and each other, and begin to plug the break. They also interact with other blood proteins to form fibrin.
Platelets contribute their hemostatic capacity via adhesion, activation and aggregation, which are triggered upon tissue injury.
