Selenium and Iodine Flashcards
3 a.a. in GPx?
Gly-Cys-Glu
what is the 21st amino acid?
selenocysteine (SEC), where Se replaces S
adding microminerals to soil is referred to as:
biofortification
things that prevent absorption of selenium
other metals, phytate
How to make protein containing SEC?
enzyme converts seryl-tRNA to SEC-tRNA during translation
examples of selenoenzymes?
glutathione peroxidase, 5’-deiodinase
how is SEC diff from GLA and OHPro?
added as a.a. during translation, whereas latter are post-translational changes
good food sources of selenium?
fish, brazil nuts, soil levels (esp. affect meat amount)
RDA fro selenium is ___mcg, and EAR is based on:
55; amount needed to maximize synth of GPx
In a region of China, this disease is Se deficiency and viral prob causing fibrosis of heart
Keshan disease
disease involving degeneration of joints, implicating Se deficiency
Kashin-Beck
high Se protects from high ___
arsenic (Bangladesh)
UL for Se is ___mcg from ___ sources
400; all
UL set based on:
hair/nail brittleness (selenosis) in area in China with high Se
UF is set at __ because symptoms are ___
2; irreversible
what does IDD stand for?
iodine deficiency disorders
particular food sources of iodine are referred to as:
goitrogens
active form of thyroid hormones is ____, transport form is ___
T3 (triiodothyronine); T4 (thyroxine)
I binds to ring of ____
tyrosine
where do we store iodide?
in thyroid gland
how is iodide diff from most microminerals?
significant urinary excretion
absorption of I is almost ____%, and in ____
100; stomach and small intestine
why can’t insulin be taken orally?
it is a protein so it would be digested
steps of thyroid hormone synth?
1) I enter thyroid cell by active transport 2) I added to thyroglobin at Tyr (Fe dependent) to make Thg-MIT 3) another I is added to Thg-MIT to make Thg-DIT 4) 2 Thg-DIT make T4, DIT + MIT = T3 5) T3/4 remove from Thg and release to plasma
low T3 triggers this hormone:
thyroid stimulating hormone (thyrotropin)
hyperplasia of thyroid gland because of TSH stim in I-deficiency
goitre
goitre in western countries is possibly cause by:
surgery on nodules, use of radioactive iodide (gamma rays), sometimes cancer
T3 is found in these tissues
liver, brain, pit., brown adipose
T3 influences:
transcription, ^ BMR, heat production, ^ O2 consumption–>CNS development, linear growth
EAR is set to meet requirement for____
uptake by thyroid gland (95mcg)
RDA is SD of EAR ____%
20
the child of mother deficient during pregnancy
cretin
symptoms of cretinism?
mental retardation, neuro defects, growth abnormalities
examples of goitrogens?
thiocyanate-generators: cabbage and cassava species
when these nutrients are low, problem of I deficiency is worse
Se, Vit A, Fe
people living in ____ regions more likely have IDD prevalence
mountainous
In Canada, mandatory to add ___mcg I per gram of table salt
76
goiter is endemic in these regions
Andes, Eastern Europe, Nepal, Ethiopia
UL for I is ___mcg from __ sources
1100; all
UL for I is based on____
elevated serum TSH and goitre-like symptoms (hyperthyroidism)
