Figure 1.

Adhesion, activation and aggregation. (A) Endothelial injury in the blood vessel exposes collagen to platelets and von Willebrand factors (vWF). (B) Resting platelets attach to the exposed collagen with their glycoprotein surface receptors directly and/or via vWF mediated anchorage. (C) The platelet, upon adhesion to collagen, is activated, changes morphology and releases granular contents which activate more platelets. Activated platelets induce conformational change in a surface receptor, namely, glycoprotein receptor (GP)IIb/IIIa, which induces (D) platelet aggregation via vWF and fibrinogen. (E) Aggregated platelets form a plug at the site of the injury, thereby stopping the blood leakage temporarily. ADP: Adenosine diphosphate; TxA₂: Thromboxane A₂; vWF: von Willebrand factor; GP: glycoprotein receptors. (Figure courtesy of biorender.com).