What is the primary function of red blood cells?

The primary function of red blood cells is to transport oxygen throughout the body. This is achieved through the presence of hemoglobin, a protein found within red blood cells that binds to oxygen molecules in the lungs and carries them to tissues and organs. This transport of oxygen is essential for cellular respiration, which is the process by which cells produce energy. Without an adequate supply of oxygen, tissues cannot function effectively, leading to impaired biological processes and overall health.

While other functions, such as fighting infection and transporting nutrients, are critical in their own right, they are primarily the roles of other components of the blood, such as white blood cells and plasma, respectively. Red blood cells are specifically adapted for the efficient absorption and delivery of oxygen, making this function their primary role in the circulatory system.