What is a primary function of red blood cells?

Red blood cells, also known as erythrocytes, play a crucial role in transporting oxygen from the lungs to the tissues throughout the body. This function is primarily carried out by hemoglobin, a protein within red blood cells that binds to oxygen molecules. When red blood cells pass through the lungs, they pick up oxygen, which is then released to body cells as required for metabolism and energy production.

This oxygen transport is vital for sustaining life, as cells rely on oxygen for aerobic respiration—the process that generates ATP, the energy currency of the cell. In addition to oxygen transport, red blood cells also assist in carrying carbon dioxide, a waste product of cellular respiration, back to the lungs for exhalation. This dual role in gas exchange underlines the red blood cells' primary function in the circulatory system and their central importance to overall physiological functions.