human iron metabolism human iron metabolism human iron metabolism is the set of chemical reactions that maintain human homeostasis of iron at the systemic and cellular level. iron is both necessary to the body and potentially toxic. controlling iron levels in the body is a critically important part of many aspects of human health and disease. hematologists have been especially interested in systemic iron metabolism, because iron is essential for red blood cells, where most of the human body's iron is contained. understanding iron metabolism is also important for understanding diseases of iron overload, such as hereditary hemochromatosis, and iron deficiency, such as iron-deficiency anemia. diagram showing a generalized view of cellular iron homeostasis in humans. iron import can occur via endocytosis of transferrin receptor 1 or via ferrous iron importers dmt1 and zip14, which require the activity of iron reductases such as steap2, sdr-2 and dcytb. intracellular iron can be stored in ferritin and used for protein biosynthesis, or to generate reactive oxygen species (ros) and regulate transcription via iron-responsive element-binding proteins (irp1/2). export occurs through ferroportin, often aided by hephaestin (hp) and/or ceruloplasmin (cp), and repressed by hepcidin. importance of iron regulation structure of heme b; "fe" is the chemical symbol of iron, "ii" indicates its oxidation state. iron is an essential bioelement for most forms of life, from bacteria to mammals. its importance lies in its ability to mediate electron transfer. in the ferrous state (fe2+), iron acts as an electron donor, while in the ferric state (fe3+) it acts as an acceptor. thus, iron plays a vital role in the catalysis of enzymatic reactions that involve electron transfer (reduction and oxidation, redox). proteins can contain iron as part of different cofactors, such as iron–sulfur clusters (fe-s) and heme groups, both of which are assembled in mitochondria. cellular respiration main article: cellular respiration human cells require iron in order to obtain energy as atp from a multi-step process known as cellular respiration, more specifically from oxidative phosphorylation at the mitochondrial cristae. iron is present in the iron–sulfur cluster and heme groups of the electron transport chain proteins that generate a proton gradient that allows atp synthase to synthesize atp (chemiosmosis). heme groups are part of hemoglobin, a protein found in red blood cells that serves to transport oxygen from the lungs to other tissues. heme groups are also present in myoglobin to store and diffuse oxygen in muscle cells. oxygen transport