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

The primary function of red blood cells (RBCs) is to carry oxygen to body tissues. This is accomplished through hemoglobin, a protein within RBCs that binds to oxygen in the lungs and releases it as the cells circulate through the body's tissues. The delivery of oxygen is crucial for cellular respiration, the process by which cells generate energy. Without sufficient oxygen, tissues and organs cannot function properly, leading to various health issues.

While RBCs also play a role in transporting carbon dioxide back to the lungs for exhalation, their main and most significant role is focused on delivering oxygen, which is essential for survival. Other functions of the blood, such as fluid balance, immune response, and clotting, are primarily handled by different blood components, such as white blood cells and platelets. Therefore, the role of RBCs is uniquely aligned with oxygen transport, making it their most critical function.