In a healthy adult, approximately how long is the lifespan of an erythrocyte (red blood cell) in circulation?

• A. About 10 days
• B. About 365 days
• C. About 30 days
• D. About 120 days

Answer: (D)

Verified step by step guidance

1. Understand that erythrocytes, or red blood cells, have a finite lifespan due to their lack of nucleus and organelles, which limits their ability to repair themselves.
2. Recall that the typical lifespan of an erythrocyte in a healthy adult is well-established through physiological studies and is commonly cited in anatomy and physiology literature.
3. Recognize that the lifespan is measured in days and is significantly longer than 10 or 30 days, but much shorter than a full year (365 days).
4. Identify that the average lifespan of an erythrocyte is approximately 120 days, which balances the need for efficient oxygen transport with the natural degradation of the cells.
5. Conclude that the correct answer is 'About 120 days' based on standard physiological knowledge of red blood cell turnover.