What is the main function of hemoglobin in the blood?

Hemoglobin primarily functions to transport oxygen from the lungs to various tissues throughout the body. This protein, found in red blood cells, has a strong affinity for oxygen, allowing it to bind effectively in the oxygen-rich environment of the lungs. Once it reaches the tissues, hemoglobin releases this oxygen, which is essential for cellular respiration and energy production. This role is critical as nearly all cells in the body require oxygen to perform metabolic processes.

While options like carrying nutrients, regulating blood pressure, and producing antibodies describe important functions in the body, they do not pertain to the specific role of hemoglobin. Nutrients are typically transported by different proteins and substances, while blood pressure regulation involves a complex interaction of various factors including blood vessel function and hormonal signals. Antibodies are produced by the immune system to protect the body against pathogens, which is a separate function from the oxygen transport role of hemoglobin.