What is the primary role of hemoglobin in red blood cells?

The primary role of hemoglobin in red blood cells is to carry oxygen. Hemoglobin is a protein that binds oxygen molecules in the lungs, where the concentration of oxygen is high, and releases them in tissues and organs, where the oxygen concentration is lower. This process is crucial for the aerobic metabolism of cells, enabling them to produce energy efficiently.

While it is true that red blood cells and hemoglobin also play roles in transporting carbon dioxide back to the lungs and maintaining blood pH to some extent, the primary and most critical function is the transport of oxygen. This function is essential for sustaining life, as oxygen is vital for cellular respiration and energy production in the body. Hemoglobin's ability to reversibly bind oxygen makes it an efficient transport molecule in the circulatory system.