Iodine

Question 1

Major fxn

Answer 1

Master regulator of metabolism / syn of thyroid hormones

Question 2

What determines availability of Iodine in soils

Answer 2

Solubility in soil = different bioavailability
- Reduced in heavy floods
Location

Question 3

Best reliable source of Iodine

Answer 3

Food from the sea / salt (fortified)
Also in: meat, eggs, beef, bean, potato (60), bread, milk

Question 4

RDA for Iodine

Answer 4

Adults - 150 ug/day
Pregnant - 220ug/day
Lactating - 290ug/day

Question 5

How much is stored and where is iodine

Answer 5

15-20mg in body
65% stored in thyroid gland (rest in kidneys and other glands)
- Thyroid can concentrate iodine 100-fold more than plasma levels *

Question 6

Source of excretion?

Answer 6

Kidney - normal levels are 50 ug/g iodine

Question 7

Thyroglobulin

Answer 7

precursors to thyroid hormones (from nucleus) - iodine gets added through thyroid peroxidase

Question 8

DIT Vs. MIT

Answer 8

DIT - two MIT - 1
T4 - 2 DIT (turns process of)
T3 - 1 MIT + 1 DIT (Active)

Question 9

How do we activate T3

Answer 9

through de-iodinate enzymes
Type1: Liver, kidney, thyroid
Type 2: Brain, adipose, pituitary

Question 10

Thyroid H and Syn

Answer 10

TSH in bloodstream
Activates cAMP - Protein K
Removes TG(3/4) from colloid
Lysosomes help move to Blood Stream from follicular cell
T3 binds nuclear receptors and activates syn of genes

Question 11

T3 regulates

Answer 11

Mitochondrial protein synthesis
Lipid metabolism
CHO metabolism
Protein metabolism
Ion transport
Muscle contraction.

Question 12

What is T4 responsible for

Answer 12

Neg feedback to hypothalamus + Ant Pit
can also convert to T3

Question 13

hypothyroidism

Answer 13

Insufficient dietary iodine to synthesize T4
Increase Thyroid stimulating hormone - enlargement of thyroid follicles - Goiter
Cause: increase goitrogens: cabbage, spinach, radish, soybeans, peach, strawB