What is the primary function of red blood cells?

The primary function of red blood cells is to transport oxygen throughout the body. These cells contain hemoglobin, a specialized protein that binds to oxygen in the lungs and carries it to tissues and organs. This delivery of oxygen is crucial for cellular respiration, which provides the energy needed for cells to function. In addition to oxygen transport, red blood cells also help in the removal of carbon dioxide, a waste product of metabolism, by carrying it back to the lungs for exhalation.

Understanding this role is vital, as it highlights how essential red blood cells are to maintain overall health, ensuring that every part of the body receives the oxygen necessary for survival and function. Other answers, while important in their own rights, do not pertain to the direct role of red blood cells in the circulatory system.