What is the function of red blood cells?

• A. To regulate blood pressure
• B. To transport nutrients from the digestive system
• C. To transport oxygen from the lungs to the body tissues
• D. To fight infections in the bloodstream

Answer: (C)

Red blood cells primarily function to transport oxygen from the lungs to the body tissues, which is essential for cellular metabolism and energy production. They are equipped with hemoglobin, a protein that binds oxygen in the lungs and releases it in the tissues where it is needed. This oxygen transport is vital because cells require oxygen to perform aerobic respiration, a process that generates the energy necessary for various cellular activities. Additionally, red blood cells also play a role in transporting carbon dioxide, a waste product of metabolism, from the tissues back to the lungs for exhalation, helping to maintain the acid-base balance in the body.

The other functions listed in the options do not accurately represent the main role of red blood cells. For instance, regulating blood pressure is primarily managed by the vascular system and the heart through mechanisms such as vasoconstriction and dilation, as well as fluid volume regulation. The transport of nutrients from the digestive system is mainly the job of plasma, while white blood cells are responsible for fighting infections, not red blood cells. Thus, the primary and most accurate function of red blood cells is indeed the transport of oxygen.