What is the primary function of red blood cells?

The primary function of red blood cells is to transport oxygen from the lungs to the body tissues. This is achieved through the protein hemoglobin, which binds to oxygen in the lungs and releases it in tissues where it is needed for cellular respiration. Oxygen is essential for the production of energy in body cells, facilitating various metabolic processes that sustain life.

While red blood cells can contribute to other functions in a limited manner, such as playing a role in the transport of carbon dioxide back to the lungs for exhalation, their main role is unequivocally the delivery of oxygen. Other functions mentioned, such as transporting nutrients or regulating body temperature, fall outside the primary role of red blood cells, as those are primarily managed by other components of the circulatory system, such as plasma and specialized cells.