What is the primary purpose of red blood cells in the body?

The primary purpose of red blood cells (RBCs), also known as erythrocytes, is to transport oxygen throughout the body. They achieve this function by binding oxygen in the lungs, where oxygen concentration is high, and then delivering it to tissues and organs that require it for metabolic processes. This transport is facilitated by hemoglobin, a protein within the red blood cells that has a high affinity for oxygen.

In addition to oxygen transport, red blood cells also play a role in the transport of carbon dioxide, but their primary and most critical function is oxygen delivery. This essential role is crucial for cellular respiration, the process by which cells produce energy. Without adequate oxygen supply, tissues would not be able to perform their functions effectively, leading to systemic issues in the body.

While red blood cells are vital for maintaining the body's respiratory function, other options—such as clotting and immune response—are primarily facilitated by different components of the blood. Platelets and clotting factors are responsible for blood coagulation, whereas white blood cells are key players in the immune response. Therefore, the primary function of red blood cells is unequivocally centered around oxygen transport.