What is the primary function of red blood cells?

The primary function of red blood cells is to carry oxygen from the lungs to the body cells. These specialized cells are equipped with a protein called hemoglobin, which binds to oxygen molecules. When breathing occurs, oxygen enters the lungs and binds to hemoglobin in the red blood cells. These cells then circulate through the bloodstream, delivering oxygen to tissues and organs where it is essential for cellular respiration and energy production.

While nutrients, hormones, and immune responses are vital for the body's overall function, they are not the primary responsibility of red blood cells. Instead, nutrients are transported by other blood components, such as plasma, and the immune system relies on white blood cells to defend against diseases. Hormones are also carried by the circulatory system but through a different mechanism that involves specific transport proteins and other cells. Thus, the focus of red blood cells remains on oxygen transport, which is crucial for maintaining the body's metabolic processes.