Final answer:
Platelets aggregate through interaction with exposed collagen and endothelial lining, assisted by von Willebrand factor and the release of chemicals from their granules.
Step-by-step explanation:
Platelet aggregation occurs through the interaction of platelets with exposed collagen and endothelial lining.
When platelets encounter an area of vessel rupture, they begin to clump together and bind to the exposed collagen and endothelial lining. This process is assisted by a glycoprotein called von Willebrand factor. As platelets collect, they release chemicals from their granules into the plasma, further contributing to hemostasis.