Upload
abdullah-bin-khurram
View
143
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Made for a PBL session in 2nd Year MBBS in Rawalpindi Medical College, Pakistan in 2011.
Citation preview
Iron Absorption From GIT
By: Abdullah Bin Khurram
Fe2+ Fe3+
Haeme
Food Iron
sugars citrates
Lactate
Aminoacids
Bile
Apotransferrin
Apotransferrin Fe2+Transferrin
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
Oxidation
Oxidation
Hemin enters the mucosal cells
Mucosal Cell
• Hemin is cleaved to release iron
• Haeme may be absorbed as such into the blood, where it is bound by HEMOPEXIN
• 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
3
4
Adult Male MenstruatingFemale
PregnantFemale
Min Value
Max Vale
• They vary as follows as per rate of absorption:
Factors increasing iron Uptake
• Vitamin C (aids Fe3+ → Fe2+)
• Citrate
• Alcohol
• Fructose
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)