Deoxyhemoglobin is a form of hemoglobin, the protein in red blood cells responsible for transporting oxygen throughout the body. When hemoglobin binds to oxygen in the lungs, it becomes oxyhemoglobin. Once it releases oxygen to the tissues, it transforms into deoxyhemoglobin, which has a different shape and color, appearing darker than its oxygenated counterpart. Deoxyhemoglobin plays a crucial role in the body's respiratory process. It helps maintain the balance of oxygen and carbon dioxide in the blood. When tissues use oxygen, they produce carbon dioxide, which deoxyhemoglobin can help transport back to the lungs for exhalation.