Haemostasis — MFDS Part 1 MCQ

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ModeratePhysiologyHaemostasisMFDS Part 1

At a site of vascular injury under high-shear conditions, which process is the principal role of von Willebrand factor in primary haemostasis?

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Correct answer: C — Initial platelet tethering and adhesion to exposed subendothelium via GPIb

Von Willebrand factor mediates the initial capture and adhesion of platelets at damaged vascular subendothelium, particularly under high shear. It binds exposed subendothelial matrix and platelet GPIb, forming an adhesive bridge. It also carries and protects factor VIII in plasma. Stable platelet aggregation is primarily mediated by activated GPIIb/IIIa binding fibrinogen, so B is not the best answer. Fibrinolysis is mediated by plasmin; fibrin cross-linking by factor XIIIa; and thrombin inhibition principally by antithrombin. These are separate components of clot breakdown, clot stabilisation and physiological anticoagulation, respectively.

Reference: Szántó T, Joutsi-Korhonen L, Deckmyn H, Lassila R. New insights into von Willebrand disease and platelet function. Seminars in Thrombosis and Hemostasis. 2012;38(1):55–63. https://pubmed.ncbi.nlm.nih.gov/22314604/