Iron is the element to which oxygen binds on a hemoglobin molecule within an erythrocyte. Small amounts of iron are lost from the body via urine, feces, sweat and cells sloughed from the skin. Women lose additional amount via menstrual blood. In order to remain in iron balance, the amount of iron lost from the body must be replaced by ingestion of iron containing foods.
Disruption of iron balance can result in either iron deficiency leading to inadequate Hemoglobin production or excess of iron in the body (hemochromatosis) leading to abnormal iron deposits and damage to various organs like liver, heart etc.
The hemostatic control of iron balance resides primarily in the intestinal epithelium, which actively absorbs iron from ingested food. Normally, only a small fraction of ingested iron is absorbed. However, this fraction is increased or decreased in a negative feedback manner, depending upon the state of body's iron balance- the more iron in the body, the less ingested iron is absorbed.
The body has a considerable store of iron, mainly in liver, bound up in a protein called ferritin. Ferritin serves as a buffer against iron deficiency. About 50% of total body iron is in hemoglobin, 25% in the other heme-containing proteins in the cells of the body and 25% is in liver ferritin.
The recycling of iron is very efficient. As old erythrocytes are destroyed in the spleen their iron is released into the plasma and bound to an iron transport plasma protein called transferrin. Transferrin delivers almost all of this iron to the bone marrow to be incorporated into new erythrocytes.
Recirculation of erythrocyte iron is very important because it involves 20 times more iron per day than the body absorbs and excretes.
Disruption of iron balance can result in either iron deficiency leading to inadequate Hemoglobin production or excess of iron in the body (hemochromatosis) leading to abnormal iron deposits and damage to various organs like liver, heart etc.
The hemostatic control of iron balance resides primarily in the intestinal epithelium, which actively absorbs iron from ingested food. Normally, only a small fraction of ingested iron is absorbed. However, this fraction is increased or decreased in a negative feedback manner, depending upon the state of body's iron balance- the more iron in the body, the less ingested iron is absorbed.
The body has a considerable store of iron, mainly in liver, bound up in a protein called ferritin. Ferritin serves as a buffer against iron deficiency. About 50% of total body iron is in hemoglobin, 25% in the other heme-containing proteins in the cells of the body and 25% is in liver ferritin.
The recycling of iron is very efficient. As old erythrocytes are destroyed in the spleen their iron is released into the plasma and bound to an iron transport plasma protein called transferrin. Transferrin delivers almost all of this iron to the bone marrow to be incorporated into new erythrocytes.
Recirculation of erythrocyte iron is very important because it involves 20 times more iron per day than the body absorbs and excretes.
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