RN Nursing · Pathophysiology · Practice question
What erythrocyte feature enhances oxygen-carrying capacity?
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Aerobic respiration
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Presence of nucleus
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Rigid shape
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✓
Biconcave shape
Answer & explanation
Correct: Biconcave shape
The biconcave disc shape of mature erythrocytes is a key structural adaptation that significantly enhances their oxygen-carrying capacity. This shape increases the surface area-to-volume ratio compared to a simple sphere, allowing for more efficient gas exchange across the cell membrane. Additionally, the biconcave shape allows the cell to deform and flex as it passes through narrow capillaries, ensuring oxygen delivery to the smallest vessels. The absence of a nucleus and organelles creates more internal space for hemoglobin, the protein responsible for oxygen transport. The option citing aerobic respiration is incorrect because mature red blood cells actually rely on anaerobic glycolysis for energy; they have no mitochondria and do not perform aerobic respiration. The presence of a nucleus is incorrect because mature erythrocytes have ejected their nucleus during maturation, which is actually an advantage that frees space for hemoglobin. Rigid shape is the opposite of what is needed — rigidity would impair passage through capillaries and reduce oxygen delivery to peripheral tissues. Understanding the structure-function relationship of erythrocytes is foundational to interpreting conditions such as hereditary spherocytosis, sickle cell disease, and other red cell disorders.
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