Iron Flashcards
Function of iron
Many enzymes and proteins, including haemoglobin
Free iron is toxic to cells because..
It acts as a catalyst in the formation of free radicals
Absorption of iron occurs in the..
Duodenum and upper jejunum
What facilitates the uptake of non-haem ferrous iron (Fe2+) from the intestinal lumen?
The transporter protein Divalent Metal Transporter 1 (DMT1), located on the apical surface of enterocytes
Fe3+ in the intestinal lumen must be reduced to Fe2+ by ___________ before uptake by DMT1
Duodenal cytochrome B reductase (DcytB)
The iron within enterocytes can either be stored as ________, or transferred into the bloodstream via the protein ________
The iron within enterocytes can either be stored as ferritin, or transferred into the bloodstream via the protein ferroportin
Once in the blood, iron is bound to the transport protein ____________, and is mostly transported to bone marrow for ____________
Once in the blood, iron is bound to the transport protein transferrin, and is mostly transported to bone marrow for erythropoiesis
Some iron is taken up by __________ in the reticuloendothelial system as a storage pool
Macrophages
The absorption of iron is primarily regulated by a peptide called _________, which is expressed by the liver
The absorption of iron is primarily regulated by a peptide called hepcidin, which is expressed by the liver
Function of hepcidin
Directly binds to ferroportin, resulting in its degradation and therefore preventing iron from leaving the cell
Inhibits transcription of the DMT1 gene, thus reducing iron absorption
T or F: The human body has no specific mechanism for iron excretion, and therefore regulating iron absorption to match the natural losses, is a crucial part of iron metabolism
True
Approximately 1-2mg of iron is lost from the body each day from the..
Skin and gastrointestinal mucosa
A well-balanced diet contains sufficient iron to balance this loss, as approximately 10% of the 10-20 mg of dietary iron in a balanced diet is absorbed each day
Haem iron is from ________ sources, but non-haem iron is from..
Haem iron is from animal sources, but non-haem iron is from whole grains, nuts, seeds, legumes, and leafy greens.
Haem iron is more readily absorbed than inorganic iron which consists of both..
Ferric (Fe3+) and ferrous (Fe2+) iron
Ferric iron must first be reduced to the ________ form before it is absorbed
Ferrous
On a daily basis, only a small fraction of the total iron requirement is gained from the diet. Most of the iron requirement is met from..
Recycling of iron within the reticuloendothelial system, which is released from storage and returned to the active pool
Iron is stored in two forms..
Ferritin and its insoluble derivative haemosiderin
T or F: All cells have the ability to sequester iron as either ferritin or haemosiderin
True
The highest concentrations of stored iron are in the..
Liver, spleen, and bone marrow
What is HHC?
Autosomal recessive disease characterised by excessive absorption of dietary iron
In HHC, the defective gene resides on chromosome ___ and codes for a protein called ____
In HHC, the defective gene resides on chromosome 6 and codes for a protein called HFE
Summary of iron metabolism and storage
Iron is present in which three things?
Haemoglobin
Myoglobin
Enzymes eg cytochromes
Fe2+ ion sits in the ________ ring
Prophyrin
