What is the primary function of erythrocytes?

The primary function of erythrocytes, or red blood cells, is to transport oxygen from the lungs to the tissues throughout the body and carry carbon dioxide from the tissues back to the lungs for exhalation. This vital role is accomplished through the protein hemoglobin, which binds oxygen in the lungs and releases it in the surrounding tissues where it's needed for cellular respiration. Erythrocytes are specialized for this task due to their biconcave shape, which provides a large surface area for gas exchange and allows them to deform as they pass through narrow capillaries.

In addition to their role in gas transport, erythrocytes also play a part in maintaining acid-base balance (pH) in the blood. Their efficient functioning is crucial for sustaining metabolic processes and overall cellular health, underlining why their primary role is centered around the transport of oxygen and carbon dioxide.