iron Flashcards
how does iron circulate in blood?
2Fe3+ bound to 1 transferrin
where is Fe stored? in what form?
stored as Fe3+ in ferritin, located mostly in liver and RE system
what is normal transferrin saturation? when is anemia considered?
normal is 30%
anemia is 20% and below
what happens to iron in the stomach?
converted from Fe3+ to Fe2+ by acid
where is iron absorbed?
enterocytes in the duodenum
what is responsible for iron import into enterocytes?
DMT1, intake of Fe2+
how does iron exit the enterocyte?
ferroportin as Fe2+
how is iron loaded to transferrin?
converted to Fe3+ by ferroxidase, then binds apotransferrin to form transferrin
what is the dietary regulator of iron absorption?
iron accumulation will decrease DMT1 activity
what is hepcidin?
peptide that controls the amount of iron absorbed by binding/inactivating ferroportin
what regulates iron uptake by cells?
IRP-1
what are the actions of IRP-1 when iron in a cell is low?
-decreases ferritin synthesis
-increases transferrin receptor synthesis
increases available Fe
what is the main cause of hereditary hemochromatosis?
mutation in HFE gene = lack of hepcidin = iron absorbed too efficiently and released from macrophages = increased circulating iron
what is the overall cause of ACD?
increased hepcidin from increased circulating IL-6
what is the link between HH and ACD?
hepcidin
HH = dec
ACD = inc
