SCIENCE
CIRCULATORY SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Uncertain
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120 days
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180 days
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As long as the individual survives
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Detailed explanation-1: -Normal human red blood cells have an average life span of about 120 days in the circulation after which they are engulfed by macrophages. This is an extremely efficient process as macrophages phagocytose about 5 million erythrocytes every second without any significant release of hemoglobin in the circulation.
Detailed explanation-2: -In practice there is considerable variation in the lifespan of human RBC. In a normal individual with a mean RBC lifespan of 115 days, this value may vary between 70 and 140 days [1, 2].
Detailed explanation-3: -Human red blood cells (RBCs) are normally phagocytized by macrophages of splenic and hepatic sinusoids at 120 days of age. The destruction of RBCs is ultimately controlled by antagonist effects of phosphatidylserine (PS) and CD47 on the phagocytic activity of macrophages.
Detailed explanation-4: -So, the correct answer is ‘120 days’
Detailed explanation-5: -Red blood cells provide oxygen to body tissues. Normally, red blood cells last for about 120 days in the body.