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20 Cards in this Set
- Front
- Back
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Which form of Iron is most bio-available
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heme
ferrous ferric elemental |
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which form of iron is most abundant
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ferric
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Which two things lower bio-availability
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antacids
achlohydria (needs acidic ph) |
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Heme Iron Absorption
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taken up in tact then degraded by heme oxygenase (HO-1)
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Non-heme iron absorption
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DMT1 is a specific carrier for Fe2+
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Cytosolic Iron
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common pool of heme/nonheme
bound by mobilferrin-like transport proteins |
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Basolateral surface- only known iron exporter
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ferroportin (FPN) into blood
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why is iron always associated with a protein and is transported/stored in the oxidized ferric state?
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ferrous unbound catalyzes OH radical in the fenton reaction
can damage almost every cellular component |
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Transferrin
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abundant serum protein that binds Fe3+ (can bind 2)
transferrin = iron transport 0- apoferric transferrin 1- monoferric transferrin 2-diferric transferrin |
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Iron uptake by cells
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Transferrin receptor!!
endocytosis into the cell as endosome iron is released into the cell and apotransferrin and transferrin receptor are recycled |
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ferritin
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intracellular protein used to store iron- in all cells but especially macrophages of spleen, liver, and bone marrow
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whats the best way to measure body iron stores
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serum ferritin level
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hemosiderin
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another form of ferritin-partially degraded in lysosomes. It contains 30% more stored
iron than ferritin seen in conditions of iron overload. |
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What are the 4 cells ferroportin is found in
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Macrophages (export iron from RBC degradation)
- Hepatocytes (export iron from storage) - Duodenal enterocytes (export iron from diet) - Placental trophoblasts (export iron to the embryo) |
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hepcidin
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AA protein made by the liver hepatocytes- controls the iron abs/mobilization
binds ferroportin and degrades it- prevents iron release from ferroporting containing cells when iron is high |
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When there is low hepcidin
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ferroportin is high
increased iron export from enterocyte (increased absorption) and increased export from macrophages/hepatocytes |
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High Hepcidin
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ferroportin is low
decresed export/absorption increased iron stores |
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Hepcidin deficiency
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can be hereditary hemochromatosis, results in uncontrolled release of iron from macrophages/enterocytes
increased iron= more OH radicals |
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How is hepcidin controlled
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positive regulators- increase hepcidin levels: increased iron availability
negative: decrease hepcidin decreased iron availability hypoxia hemochromatosis increased erythroid demand |
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1 ml of blood has ____ iron?
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0.5 mg of iron/ml of blood
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