What is the primary function of red blood cells (erythrocytes)?

The primary function of red blood cells, or erythrocytes, is to transport oxygen from the lungs to the tissues and return carbon dioxide from the tissues back to the lungs for exhalation. This is facilitated by hemoglobin, a protein within red blood cells that has a high affinity for oxygen, allowing efficient capture and release of oxygen during circulation. The ability to carry carbon dioxide back to the lungs also plays a crucial role in maintaining the acid-base balance of the blood and the overall respiratory process.

While fighting infections is an important function of the immune system, it is carried out mainly by white blood cells, not red blood cells. Hormonal transport is a function of the circulatory system but typically involves proteins in plasma rather than red blood cells themselves. Body temperature regulation involves various physiological mechanisms, including blood flow and metabolic processes, and is not a direct function of red blood cells. Therefore, the accurate understanding of the primary role of erythrocytes highlights their essential contribution to oxygen transport and carbon dioxide removal in the body.