Week 12 Flashcards
(42 cards)
What are the two forms of iron in the body?
Heme iron (ferrous iron): Fe2 +, for absorption
Non-heme iron (ferric iron): Fe3 +, for transport
How and where is iron absorbed in the body?
In small intestine, mediated by carrier proteins
What converts Fe3+ to Fe2+?
Ferrireductase in the brush-border
What are the two carrier proteins for iron and what are their functions?
Ferritin: binds and stores iron in enterocytes (and other tissues)
Ferroportin: transports iron out of enterocytes when supplies are low for release into the blood
What are the ferroxidase enzyme used to convert Fe2+ to Fe3+
hephaestin in enterocytes
ceruloplasmin in the blood
How is iron transported?
As Fe3+
Where and how is iron stored?
In the liver, bone marrow, spleen, bound to ferritin or hemosiderin
What are the functions of iron
- Hemoglobin: Transport of oxygen and carbon dioxide
- Myoglobin: transport of oxygen
- Oxidation reduction reactions
- Immune system function
- Energy metabolism
- Alcohol and drug metabolism
- Cofactor in enzymes involved in making neurotransmitters
Where is iodine absorbed?
Small intestines
what decreases the absorption of iodine?
Goitrogens foods decrease iodine availability for absorption
Turnips, cabbage, brussels sprouts, broccoli, potatoes, cassava, peanuts, soy, peaches, strawberries
how is iodine transported?
Bound to thyroglobulin, taken to the thyroid gland
Sodium-dependent transport system traps iodine in thyroid gland for hormone synthesis
Where is iodine stored?
muscle, thryiod gland, skin
What are the two forms of iodine and what do they function as?
T4 is the form of thyroid hormone in the circulation
T3 is the active hormone form
A Goiter and cretinism is the result of what deficiency?
Iodine
How is the absorption of zinc increased?
consumed in small amounts zinc defiency (increase need) certain amino acids presence of riboflavin yeast in leavened bread increases absorption x 10 by cleaving phytates from Zn
What impairs the absorption of zinc?
polyphenols, high fiber due to phytates alcohol phytic acid and fiber in whole grains excessive zinc intake high non heme iron intake good zinc status
When absorbed: zinc promotes the synthesis of what?
metallothionein in enterocytes to bind zinc and keep it in there for controlled release
What is Metallothionein?
a binding protein (similar to ferritin) that blocks zinc’s movement into bloodstream (prevents excess absorption into the bloodstream)
What does zinc deficiency lead to?
Anorexia
Leads to: delayed growth, poor development in children
Dermatitis, impaired vitamin A, D and thyroid hormone function, alopecia, poor wound healing
Decreased taste and immune function
where how is copper absorbed?
small instestion
diffusion and active transport
What decreases copper absorption?
large intake of Cu, Fe and Zn, phytates
How is copper transported in the body?
Bound to protein, e.g. albumin, taken to the liver -
Released to other tissues from the liver bound to ceruloplasmin
Where is copper stored?
iver and kidney
What can copper difficiency result from?
Menke’s disease: genetic disorder interfering with copper transport and adequate delivery to tissues
