Question

Place the steps of iron metabolism in order. Start with absorption from the intestine, and end with its distribution to the body.

Instructions

Answer 1

Iron metabolism in the human body starts with iron absorption in the intestine, followed by transport into mucosal cells and binding to ferritin. Iron is then transported via ferroportin into the bloodstream, where it binds to transferrin and is distributed throughout the body. Excess iron is stored as ferritin and hemosiderin, and released upon stimulation by erythropoietin for red blood cell production.

Step-by-step explanation:

Steps of Iron Metabolism

The metabolism of iron in the human body involves several key steps, starting with the absorption of iron from the intestine. Iron absorption mainly occurs in the duodenum and the proximal jejunum, where the iron is primarily in the ferric form (Fe³⁺). The acidic pH of the gastrointestinal tract favors this absorption. Once absorbed, iron is transported across mucosal cells via active transport. Within these cells, iron binds to the protein ferritin, which creates iron-ferritin complexes for temporary storage.

When the body's iron requirements increase, such as during periods of bleeding or for females during menstruation, there is an increase in the uptake of iron from the intestine and a quicker release of iron into the bloodstream. Ferroportin transports iron across intestinal cell plasma membranes into tissue fluid, where it is then released into the blood. Once in the bloodstream, iron is bound to transferrin and transported to areas where it is needed, especially to the red bone marrow for erythrocyte production.

In cases where iron is not immediately needed, it can be stored in the liver, spleen, and bone marrow in the form of ferritin and hemosiderin. The release of stored iron is stimulated by erythropoietin (EPO), which enhances the production of red blood cells (erythrocytes).

SUMUP of Iron Metabolism Steps

1. Iron is absorbed from the intestine, specifically the duodenum and proximal jejunum.
2. Iron is transported via active transport into the mucosal cells and binds to ferritin.
3. Ferroportin moves iron across intestinal cell membranes into the body.
4. Iron is bound to transferrin in the bloodstream and distributed to necessary sites.
5. Excess iron is stored as ferritin and hemosiderin in the liver, spleen, and bone marrow.
6. EPO triggers the release of iron from storage when red blood cell production is required.