Iron absorption from GIT
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Iron Absorption From GIT
By: Abdullah Bin Khurram
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Fe2+ Fe3+
Haeme
Food Iron
sugars citrates
Lactate
Aminoacids
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Bile
Apotransferrin
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Apotransferrin Fe2+Transferrin
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The receptor molecule is a transmembrane homodimer linked by disulfide bonds. An acyl group attached to the cytoplasmic tail of the molecule anchors the assembly to the plasma membrane.
Disluphide bond
Acyl group
Transferrin
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Oxidation
Oxidation
Hemin enters the mucosal cells
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Mucosal Cell
• Hemin is cleaved to release iron
• Haeme may be absorbed as such into the blood, where it is bound by HEMOPEXIN
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• Only 5 - 10% of dietary iron is absorbed, because of the “Ferritin Barrier”
• Rate of Iron absorption:– Adult male: abt 0.5 – 1 mg per day
– Menstruating Female abt 1 – 2 mg per day
– Pregnant female abt 3 – 4 mg per day
0
1
2
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4
Adult Male MenstruatingFemale
PregnantFemale
Min Value
Max Vale
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• They vary as follows as per rate of absorption:
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Factors increasing iron Uptake
• Vitamin C (aids Fe3+ → Fe2+)
• Citrate
• Alcohol
• Fructose
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Inhibitors of Iron Absorption
• Plant phytates– Tightly bind to iron and prevent its absorption– Present in cereals
• Plant tanins
• Phosphates and oxalates
• Calcium
• Pancreatic juice (Ganong)