When the intima of a blood vessel is disrupted, as happens after a cut or the rupture of an atherosclerotic plaque, subendothelial collagen and von Willebrand factor are exposed to circulating blood.

• 当血管内破裂时，血小板就会黏附、活化、聚集。动脉粥样硬化斑块切开或破裂，内皮下胶原和vWF暴露于循环血液时，也是如此。