The primary function of red blood cells is to transport oxygen from the lungs to the body’s tissues and carry carbon dioxide back to the lungs for exhalation. They contain a protein called hemoglobin, which binds with oxygen, allowing for efficient gas exchange. Red blood cells are critical for maintaining cellular respiration and energy production within the body. Each red blood cell can travel through the bloodstream numerous times a day, facilitating this essential function. A healthy number of red blood cells is crucial for overall health, as a deficiency can lead to conditions like anemia, affecting energy and vitality.