What is the function of hemoglobin in red blood cells?

Hemoglobin's primary function in red blood cells is to bind to oxygen in the lungs and transport it to various tissues throughout the body. This process is crucial for delivering the oxygen required for cellular respiration, which is how cells generate energy. Hemoglobin contains iron, which allows it to effectively capture oxygen molecules, forming oxyhemoglobin when it binds to oxygen in the lungs. Once it reaches the tissues, hemoglobin releases the oxygen, which is utilized by cells to produce energy.

Understanding this function illustrates the vital role hemoglobin plays in respiratory physiology and systemic circulation. The other options do not accurately reflect the primary role of hemoglobin in red blood cells: transporting nutrients is primarily the function of plasma, blood clotting involves platelets and clotting factors, and body temperature regulation is achieved through various mechanisms, including blood flow, but is not a direct function of hemoglobin.