Iron Metabolism Flashcards
Iron
Transition metal
May be _____ or _____
2+ or 3+
Ferrous(__+)
Ferric(__+)
2
3
Ferrous(2+) “________”- ______an electron
Ferric(3+) “________”-_____an electron.
reduced; gained
oxidised; lost
DIETARY SOURCES OF IRON
Non Haem:
•______________-___% bioavailability
-Absorption enhanced by ——- agents e.g. ascorbic acid(maintains Fe2+),hydroquinone, lactate, pyruvate, succinate, fructose, sorbitol, and cysteine
-Inhibited by ______,———-,_______
Cereals, legumes,vegetables
10; reducing
tannins ,phytates, and phosphates.
DIETARY SOURCES OF IRON
Haem:
•
-_______
-_____% bioavailability -Haem is taken up intact.
meat, fish
30
_______mg of iron enters the body each day and most of them enter ______
Most of the iron seen in the plasma is from ________________________
Each day, approximately ____ mg of iron is lost from the body
The remaining body iron is stored, primarily in _______
1 to 2
haemoglobin
continuous breakdown of haemoglobin in old red cells by RE macrophages
1 to 2
hepatocytes
Iron functions
Oxygen carriers eg ________
Oxygen storage eg _______
Energy Production ________, _______
Other:
Liver detoxification (_________)
haemoglobin
Myoglobin
Cytochromes (oxidative phosphorylation); Krebs cycle enzymes
cytochrome p450
IRON COMPARTMENTS
The concentration of Iron in adult human body is usually ___mg/kg in males and ___mg/kg in females.
50
40
IRON COMPARTMENTS
_____ Iron compartments.
six
IRON COMPARTMENTS
HAEMOGLOBIN
molecular weight ____ Da
____% iron by weight.
1ml packed RBC contains approximately 1mg iron
Total body amount is 2-2.5gm.
Lower in (males or females?) .
64500
0.34
Females
IRON COMPARTMENTS
STORAGE IRON(FERRITIN)
Water (soluble or insoluble ?) protein –
Found in _______ cells of the body and tissue fluids.
Has an outer protein shell _____ and an _________________ core.
Can bind _________ atoms of Iron.
Soluble
apoferritin
iron- phosphate-hydroxide
4500-5000
IRON COMPARTMENTS
MYOGLOBIN IRON
Structurally similar to _____ but ______.
Present in (small or large?) amounts in all __________ muscles.
Haemoglobin; monomeric
Small
skeletal and cardiac
MYOGLOBIN IRON
__________ + ______________
Haem group +polypeptide chain of 150 amino acids.
IRON COMPARTMENTS
LABILE POOL
Iron leaves plasma and is bound to ___________ , then incorporated into ____ or other structures, or refluxes into plasma
membrane or cytoplasmic proteins.
heme
IRON COMPARTMENTS
TISSUE IRON
Heme proteins - ____,_______,______
Flavoproteins -__________, _______,_________
cytochromes, peroxidases, catalase
xanthine oxidase; dehydrogenases
cytochrome C reductase
IRON COMPARTMENTS
TRANSPORT IRON
Contains ___mg of Iron and turns over ____ times per day.
3
10
Smallest but most active compartment.is ???
Transport
_______ and _______ transport Iron in plasma and milk respectively.
Transferrins and lactoferrins
IRON ABSORPTION
Occurs in the ______
Taken up as ___ iron or _____ iron
1 – 2 mg iron are absorbed each day
Only ___% of dietary iron is absorbed
duodenum
ionic; haem
10
Dietary iron is usually in excess
T/F
T
Excess dietary iron is either ______, or __________ and shed into the gut
not absorbed
kept in enterocytes
IRON ABSORPTION CONTINUED
_____- Reduction Fe+++ to Fe++
______- Transport into cell
______- Storage in cell
______- Oxidises Fe++ to Fe+++
_______- Transport out
DcytB
DMT1
Ferritin
Hephaestin
Ferroportin
Non heme
2+ or 3+?
3+
Heme
2+ or 3+
2+
Which version is allowed into the enterocytes
2+ or 3+
2+
Acidic PH hinders or favors iron absorption ?
Favors
Iron deficiency hinders or favors iron absorption ?
Favors
Pregnancy hinders or favors iron absorption ?
Favors
Hypoxia hinders or favors iron absorption ?
Favors
Iron overload hinders or favors iron absorption ?
Hinders
Phytates hinders or favors iron absorption ?
Hinders
HEPCIDIN
_______ activity
Hepatic ______ protein
Master iron ______ hormone
Inactivates ______
Stops iron __________, therefore Iron is lost in stool when gut cells shed
Leads to ___eased gut iron absorption
Antimicrobial
bacteriocidal
regulatory
ferroportin
getting out of gut cells
Decr
HEPCIDIN
Increased production of Hepcidin is induced by inflammation via _____
Hepcidin synthesis and secretion are controlled by ___________,__________, and _________
Iron deficiency, hypoxia , and ineffective erythropoiesis.
interleukin 6.
HFE, hemojeuvelin, and Transferrin receptor 2.
Hepcidin deficiency targets the _____ and ______
Duodenum and spleen
Ferroportin
________ transmembrane segment protein
12 (or 10)
The only cellular iron exporter in vertebrates is _____
Ferroportin
Ferroportin
Present in the _______,_______,_________, and _________
macrophages, duodenum, hepatocytes, and the placenta