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