Perhaps the most important of iron’s functions in the body is the production of hemoglobin and myoglobin (the form of hemoglobin found in muscle tissue), and the oxygenation of red blood cells. Myoglobin takes oxygen from hemoglobin and delivers it to muscle cells, and the cytochromes, which are important for generating energy.
Iron complexed with the protein hemoglobin is necessary for oxygen transport in the blood. Iron is the central atom of the heme group, a metal complex that binds molecular oxygen (O2) in the lungs and carries it to all of the other cells in the body that need oxygen to perform their activities.
Iron is the mineral found in the largest amounts in the blood. About 25 percent of the iron in the body is stored within enterocyte in the form of ferritin, circulates in the blood. Ferritin is made up of heavy and light chain subunits, which create a spherical hollow space that can accommodate up to 4500 iron ions.
The average adult male has about 1,000 mg of stored iron (enough for about three years), whereas women on average have only about 300 mg (enough for about six months).
Ferritin can release iron if the blood has a low iron concentration, and it can help to store excess iron if the blood and tissues have a high iron concentration. Hence, ferritin functions as a "buffer" against iron deficiency and, to a lesser extent, against iron overload.
When iron stores are exhausted, the condition is called iron depletion. Further decreases may be called iron-deficient erythropoiesis and still further decreases produce iron deficiency anemia.
Blood and functions of iron
