What is the average lifespan of a normal red blood cell?

The average lifespan of a normal red blood cell is approximately 3 to 4 months. Red blood cells, or erythrocytes, are produced in the bone marrow and enter circulation, where they function primarily to transport oxygen from the lungs to various tissues and return carbon dioxide to the lungs for exhalation.

Throughout their lifespan, red blood cells undergo various physiological changes, including the loss of certain cellular components, which eventually leads to their removal from circulation primarily by the spleen and liver. This lifespan allows adequate time for the body to continually produce new red blood cells, maintaining a stable population necessary for proper oxygen delivery and overall metabolic function.

The other options do not accurately reflect the lifespan of red blood cells; while they may suggest varying periods, the physiological process dictates that the optimal and average lifespan falls within the 3 to 4-month range.