How long do erythrocytes (red blood cells) typically survive in circulation under normal physiological conditions?

• A. About 24 hours
• B. About 120 days
• C. About 30 days
• D. About 365 days

Answer: (B)

Verified step by step guidance

1. Understand that erythrocytes, or red blood cells, have a finite lifespan due to their structure and function. They lack nuclei and organelles, which limits their ability to repair themselves.
2. Recall that the typical lifespan of erythrocytes is measured in days, not hours or years, because they gradually lose flexibility and functionality as they age.
3. Recognize that under normal physiological conditions, erythrocytes circulate in the bloodstream and perform oxygen transport for a specific duration before being removed by the spleen and liver.
4. Remember that the commonly accepted average lifespan of erythrocytes in human circulation is approximately 120 days, which balances their production in the bone marrow and removal from circulation.
5. Conclude that the correct answer is 'About 120 days' based on the standard physiological lifespan of red blood cells.