Week 12 revision questions Flashcards
Factors that increase / decrease iron absorption and status
Excessive intake of calcium, zinc, phosphorus, manganese (decrease), Vit C (increase), plant sources e.g. phytic acid (decrease), HCL in stomach (enhance)
body storage will effect
Symptoms and biomarkers of iron deficiency
Tiredness, shortness of breath, fatigue doing anuthing, compromised immune, depression, spoon shapes nails
Why is a deficiency of copper a risk factor for iron deficiency?
As copper is a cofactor for ceruloplasmin (peroxidase enzyme) which converts Fe2+ to Fe3+ therefore can’t transport iron if have a deficiency in copper
Three main areas of functions of zinc with examples, that explain the important role of zinc
o catalytic - cofactor to enzymes (e.g. alcohol metabolism cofactor for alcohol dehydrogenase)
o structural - stability of protein structure (e.g. stabilization of Vit A, D, thyroid hormone receptors and stabilization of protein in bone formation
o regulatory – transcription factor to regulation gene expression (e.g. hormone signally and nerve impulse transmissions)
Why is a deficiency of selenium a risk factor for iodine deficiency?
Selenium is a cofactor required to covert T4 to T3 (bioactive form) therefore in selenium deficiency there will be a decrease in T3 and therefore impaired iodine function
What is neurological cretinism and how does it develop?
o Mentally stunted, deafness, low cognitive development and IQ, facial squinting
o Developed when iodine deficient during pregnancy
What are the health consequences of iodine deficiency
Infertility, losing baby, disfiguring baby, speech impairments, hearing and speaking issues
Where is iodine found and how does it get into our food?
o Found in iodised salt
o Gets into food by iodisation
What are the obstacles encountered by the iodised salt intervention in Tibet?
- rock salt was traded against grain and other produce by local populations but the iodised salt had to be bought a more expensive when trading
- the salt traders were spreading wrong rumours about iodised-salt saying that it was impairing animal fertility.
Why is iodine deficiency re-emerging in Australia?
o Because iodine is not longer in milk (as now use chlorine to clean milk bottles not iodine)
can be remedied by using iodized salt and fortified bread
What nutrients you have studied so far may be “at risk of deficiency” in a vegan diet? Explain your answer
o Iron – heme iron only found in animal products
Have lemon or orange juice with sources of iron; avoid tannins and polyphenols (tea, red wine) when eating iron sources
o Copper – most commonly found in seafood and more bioavailable in animal foods
avoid high fibre food, drinking tea and red wine when eating sources of zinc.
o Iodine – mainly in animal products (however there is iodized salt)
o Zinc – larger amounts of zinc are found in animal food
avoid high fibre food, drinking tea and red wine when eating sources of zinc.
Metallothionen
acts as a mucousal block for the uptake of zinc, prevents uncontrolled entry to blood stream
The protein ____ and ___ convert Fe2+-to fe3+
hephaestin and ceruloplasmin
Absorption pathway of non-heme iron
Non heme iron(Fe3+, ferric) requires ferrireductase to reduce to fe2+ (ferrous) in the brush border of snterocyte. It is than transported across membrane by DMT1. It is then stored by ferritin. Ferriportin transports iron out of enterocyte when supply is low. Then hephaestin or ceruloplasmin convert back to Fe3+ for transport.
In iron deficiency aneamia the reed blood cells look ___under the microscope
Small, pale and concaved (microcytic hypochromic anemia)
Body shows that it needs more iron by
Increasing transferrin recepters
Sequence leading to development of goiter in iodine deficiency
low circulating T4 -> TSH secreted -> hyperplasia an hypertrophy of thyroid to try capture any circulating iodine to make thyroid hormone.
Transferrin
transports iron to tissues
Hephaestin
converts Fe2+ to Fe3+ in the basolateral memebrane of enterocytes
Ferrireductase
converts Fe3+ to Fe2+ in brush border of enterocytes for absorption
Hemosiderin
stores iron in organs
Ceruloplasmin
converts Fe2+ to Fe3+ in the blood circulation for transport
Why have copper, zinc, manganese and selenium included in antioxidant formulae
All are cofactors to antioxant enzymes and thus the enzymatic antioxidant defense system to oxidative stress.
(Se ->GPX; Cu, Zn, Mn -> SOD)
Transport of iron out of the ___ cell for incorporation into serum ____ is facilitated by ___ and the conversion of ___ to ___ by ___
Intestinal; transferrin; ferroportin; Fe2+; Fe3+; ferroxidase
Ferrous food source Fe2
,meat, egg, fish
Ferric food source Fe3
spinach, kale, lentils
Cofactor of ___ (T4 to T3 conversion enzyme) is ___
iodothyronine deiodinase;selenium
Hemochromatosis is a genetic disorder causing ___ __ ____
excess iron absorption
____ is about copper accumulation (copper toxiicty)
Wilson disease
Enzymes that use copper as cofactor are
ceruloplasmin and superoxide dismustase
