Exam - Iodine Flashcards
supplement label of iodine
thyroid gland support
is iodine prevalent in most foods
no, iodine content is low
what is iodine
inorganic mineral that is highly water soluble
where is iodine found in higher concentrations
in coastal populations opposed to mountainous regions
what kind of food has high iodine concentration
seafood - especially sea greens
where does most iodine consumed come from in North America
salt fortified with potassium iodine
how many mg of iodine does iodized salt contain per g of salt
0.03
as of 2007, what percentage of the world population live in areas of iodine deficiency
29%
how can dietary iodine be found
bound to amino acids or free
what occurs to iodine in our GI tract
iodine is rapidly converted to iodide (ionic form) and absorbed
where does iodine get absorbed
mostly in stomach, a bit in small intestine
what does free iodide do in blood
circulates and can enter all tissues
where does most of free iodide accumulate
thyroid gland
what percentage of the iodine in our body is located in the thyroid gland
70-80%
what is the uptake of iodide mediated by
active transport system: Na+/I- symporter (NIS)
do all tissues depend on iodine
no, all tissues depend on thyroid hormones T3 and T4 rather than iodine itself
what happens to T3 and T4 after they are made
they are released into blood and transported by carrier proteins
is there more T4 or T3 in blood
50x more T4 than T3 in blood - but T3 is 100x more potent
what does T3 interact with
thyroid hormone receptor
what is T3 and T4 production regulated by
thyroid stimulating hormone
what occurs when T3 levels are low
the hypothalamus signals to the pituitary to release TSH
what is thyroglobulin (THG)
tyrosine-rich protein
what do thyroid hormones influence
how body stores and uses energy
things that thyroid hormones control
- breathing
- heart function
- nervous system function
- body temp
- cholesterol level
- energy balance
- brain development
- skin moisture
- menstruation
what does it mean that T3 and T4 are lipophilic
they can easily cross plasma membranes
what does T3 do in tissues
binds to THR which then binds to response elements in promoter regions of DNA to activate gene expression
examples of genes activated by T3
ATPases
Growth hormone
what does the pituitary gland release when T3 levels are low
TSH
what is occurring when iodine is deficient
the thyroid is still being stimulated by TSH to make hormones but it can’t
what is the result of the thyroid being unable to make hormones
hyperplasia
hypertrophy
hyperplasia
increase in cell number
hypertrophy
increase in cell size
result of iodine deficiency
goiter in adults
cretinism
what is a goiter
thyroid enlargement
what is cretinism
when iodine levels are low in mother, fetus does not develop properly
what does goiter lead to
thyroid cancer if left untreated
what can mild goiters be treated with
iodine supplements
what does cretinism lead to
growth and developmental abnormalities - irreversible
how many people are affected by iodine deficiency disease
over 740 million (13% of world population)
how many people have some degree of intellectual disability caused by IDD
50 million
