1. Essential and trace ions
Ions with biochemical functions and have deficiency syndrume are :
Iron and Iodide
Ions studied are :
iodide, copper,zinc,sulfur,chromium ,manganese,selenium, etc. ,iron

2. Iron :- First : Hemoproteins i – an electron carrier
Iron functions in respiratory chain are :
i – an electron carrier
ii- transport of molecular oxygen
Most iron is associated with protiens
:- First : Hemoproteins
responsible for respiration Two group proteins
and for transport oxygen .

3. An respiratory Enzyme, where iron is complexed
(a) Cytochrome – c :
An respiratory Enzyme, where iron is complexed
covalently with the protein portion in a porphyrin
ring ( heme ring ) .
Iron act as electron carrier by changing from ferrous
to the ferric form and reversibly .
Cytochrome –c role is in oxidation – reduction
process of iron .

4. ( b ) Hemoglobin and myoglobin
Hemoproteins which store and/or transport
Oxygen
- Myoglobin :
An oxygen carrying protein .
. A single polypeptide with one oxygen binding site
Binds and releases oxygen through changes in
oxygen conc. in sarcoplasma of skeletal muscle cells.

5. Hemoglobin Found in high conc. in red blood cells.
It binds to oxygen in lungs and transports it to body cells, also transports CO2 from tissues to lungs.
Hemoglobin has 4 protein chains ,each one has a heme ( porphyrin ring ) and ferrous iron .
Iron complexes O2 by using its vacant pair of non bonding electrons .

6. Uptake and release of O2 is influensed by :-
1- The oxygen tension.
2- PH
3- Presence of 2,3 diphosphoglycerate .
4- CO2 concenteration.
Patients with iron-deficiency animia have : -
a- Decreased capability for oxygen transport .
b- Decreased in hemoglobin synthesis .

7. Iron storage and transport proteins
Body handeling of iron requirments is by storage and transport proteins
a – The iron storage proteins
Found in liver, bone marrow and spleen.
Ferritin : -
A water soluble iron protein built up from apoferrtin and micelles of ferric hydroxide-phosphate complex.
Iron is stored in ferritin as Fe3+ form and released as Fe2+

8. b – Iron transport proteins
Hemosiderin
A water insoluble protein considered as
a dehydrated form of ferritin.
b – Iron transport proteins
Transferrin
Major protein in blood plasm synthesised by the liver, and it binds two ferric iron per molecule.
Transferrin releases iron to blood red cells through receptor on red cell surface.

9. Daily iron requirements : - 10-12 mg for males 12-18mg for females
2- CO transferrin+Fe transferrin.Fe 3+.CO3
( -2ransferrin.Fe3+ .co co Fe transferrin.2(Fe3+.co3
Daily iron requirements : mg for males 12-18mg for females
Iron lost in human body through bile secretions, menstrual flow & other secretions. hemorrhage,
Males lose o.6 mg iron daily
Non pregnent females lose 1.2 mg-1.8 mg iron daily
Pregnent females lose 3-4 mg daily

10. Iron disteribution in normal adults
Men Women
Hemoglobin mg mg
Myoglobin mg mg
Enzymes (transport) mg mg
Ferritin( storage) mg mg
Total mg mg

11. Iron Absorption In food diet : -
1- Iron in liver and muscle is better absorbed than iron in eggs and vegetables , because iron is bond to phytate (inositol hexaphosphate ) .
2 - Iron in hemoglobin is well absorbed , because it is still bond to porphyrin ring .
3 - Iron in wheat , corn & black beans is relatively unavailable for body use .
4 - Iron in ferritin is poorly absorbed , because the protein must firstly digested by G.I. proteases before absorption.
5 - Released iron complexed with sugars ,ascorbic acid,citric acid and amino acids .

12. Absorption mechanism
Cooking food facilitate iron ligand breakdown increasing iron availability in gut.
Low stomach PH allows reduction of ferric Fe3+ to ferrous Fe2+ with presence of reductant ( ? )
Exess bicarbonate secreated by pencreas oxidises ferrous Fe2+ to ferric Fe3+
Major iron absorption is in small intestine mostly in the duodenum .

13. Three hypothesis for absorption
1 – The mucosal blook hypothesis : -
Apoferritin
Transferrin
Apoferritin
To liver for storage
Fe3+
Fe3+
Fe3+
Ferritin
(H)
(O)
To bone marrow for use
Fe2+
Fe2+
Fe2+
Fe2+
Small intestine
Mucosal cell
Blood

14. 2 – Active transport hypothesis
Endogenous ligands
Fe 3+
Fe 2+
(H)
(O)
Biological energy compounds ATP
Fe 2+
Fe 2+
Fe 3+
Transferrin
macromolecules
Lumen of intestine
Mucosal cell
Blood

15. 3 – The ion-chelate hypothesis
Endogenous ligands
Storage
Transferrin
Fe2+
Fe3+
Fe-chelate
Fe-chelate
Fe3+
R.B.C
Excreation
Ferritin (storag )
Lumen of intestine
Blood
Mucosal cell