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28 Cards in this Set

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Which family does iodine belong to
halogen
Once absorbed in the bloodstream, where is iodine concentrated
in the thyroid gland
What is the transport system that concentrates iodine called?
the "iodine pump"
What enzyme oxidises iodine to iodide?
iodine peroxidase
What inhibits the absorption of iodine?
goitrogens
List some foods that contain goitrogens
broccoli
brussel sprouts
cabbage
kale
peaches
How is iodine excreted?
predominantly via the urine
What are the primary functions of iodine?
major action is its precursor role in the production of the thyroid hormones
What do thyroid hormones regulate?
growth
development
metabolism
reproductive function
What are the principal thyroid hormones?
thyroxine (T4)
Triioddthyronine (T3)
Where is TRH secreted?
thyrotropin-releasing hormone is secreted by the hypothalamus
Where are T3 and T4 released?
thyroid gland
Is T3 or T4 more active?
T3 (T4 secreted in greater quantities, but not as strong)
What is required for the conversion of T4 to T3?
Selenium
How does T3 function?
by binding to a nuclear receptor that controls the transcription of a particular gene and brings about the synthesis of a specific protein
What causes a goitre?
persistent stimulation by TSH due to lack of iodine and therefore lack of T4
What is the clinical deficiency of iodine?
Hypothyroidism
List some symptoms of hypothyroidism
weakness, dry skin, cold intolerance, hair loss, carpal tunnel syndrome, dyspnoea, poor memory and difficulty concentrating
What is the amount at which iodine deficiency occurs?
20mcg per day
List some foods that are good sources for iodine
Cod
Salt
Potato
Milk
Is fluoride easily absorbed?
Yes, approx 55-100% of fluorides are absorbed, depending upon the chemical form.
How is fluoride transported?
transported in the blood as:
ionic fluoride
hydrofluoric acid
bound to proteins
Where is the majority of fluoride stored?
hard tissue such as bone and teeth
How is fluoride excreted?
90% via the urine, and 10% via faecal elimination
What is the major function of fluoride?
protect against pathologic demineralisation of calcified tissue
What are some good food sources of fluoride?
tea
canned sardines
spinach
Is there an upper limit for fluoride? If yes, how much?
yes- 10mg/day
With toxic levels of fluoride, there may be:
osteosclerosis
osteoporosis
calcification of ligaments and tendons
interference with iodine metabolism- thyroid problems