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Question 351
Physiology → Haematology
Classification
Question
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An antiplatelet drug alters the function of circulating platelets. The functional effect persists for the remainder of the lifespan of the affected platelets.
Question Stem
Which combination best explains this persistence?
Options
A
Platelets are nucleated and have a lifespan of 2–5 days
B
Platelets lack mitochondria and survive for approximately 120 days
C
Platelets contain dense granules but cannot express membrane receptors
D
Platelets lack a nucleus, cannot produce new proteins and have a lifespan of approximately 9–10 days
E
Platelets are derived from lymphocytes and have a lifespan of approximately 12–15 days
Explanation
Platelets are non-nucleated fragments of megakaryocytes. Although metabolically active and able to express membrane receptors and release stored substances, their lack of a nucleus prevents production of new proteins. Antiplatelet effects can therefore persist for the remainder of the platelet lifespan, which is approximately 9–10 days.
Option Validity
A) Platelets are non-nucleated, and their lifespan is approximately 9–10 days rather than 2–5 days.
B) Platelets contain mitochondria, and 120 days is the lifespan of erythrocytes rather than platelets.
C) Platelets are metabolically active and can express membrane receptors despite lacking a nucleus.
E) Platelets are membrane-encapsulated fragments of megakaryocytes rather than derivatives of lymphocytes, and their lifespan is approximately 9–10 days.
Further Reading
Saxena. Textbook for MRCOG-1. Physiology - Haematology - Platelets, p.70.