An elderly patient with atherosclerosis experiences increased platelet aggregation. Which mechanism primarily explains why this heightened aggregation occurs in damaged blood vessels?

💡 Explanation

Exposed collagen in damaged vessels triggers platelet activation and aggregation because it provides a binding site for von Willebrand factor, which then binds to platelets. This initiates the clotting cascade. Therefore, direct collagen activation explains the heightened aggregation, rather than nitric oxide's vasodilation or antithrombin III's anticoagulant effects.

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