InnovateUs states that the main function of hemoglobin is transporting oxygen from the lungs to other parts of the body. It is an important chemical in red blood cells that carries oxygen, and performs different effect modulation and gas transport duties.
The most essential task of hemoglobin is binding oxygen to it, explains InnovateUs. The higher the amount of oxygen molecules that bind to hemoglobin, the more oxygen reaches all parts of the body. With the help of external chemical factors such as carbon dioxide, pH and DPG (2, 3-diphosphoglycerate), the hemoglobin molecules take up oxygen molecules in the lungs and send them to different tissues in the body.
On HowStuffWorks, Carl Bianco explains that oxygen is released in the capillaries to be used by the body cells. Hemoglobin carries 97 percent of the oxygen that is transported by the blood from the lungs, while the remaining three percent is dissolved in the plasma. It combines loosely with oxygen in the lungs, which has high levels of oxygen, and releases the oxygen in the capillaries, where oxygen levels are low. Every molecule of hemoglobin consists of four iron atoms, and each iron atom is capable of binding with one molecule of oxygen. The iron contained in hemoglobin gives blood a red color.