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Flashcards in thyroid hormones Deck (22):
1

what are 2 main thryroid hormones

T3 and T4

2

what are substrates and enzymes to make T3 and T4

thyroglobulin > peroxidase

3

how to tell if thyroid is active

active- small follicles - cuboidal cells
inactive - large follicles - abundant colloid

4

what are steps to make T3/4

1. transport I into colloid
2. attach I to thyroglobulin
3. phagocytose T3/4
4. back into blood

5

what is iodine requirment

150ug/day

6

how does T3/4 circulate

protein bound (TBG, albumin, transthyretin)

7

what up-regs thyroid binding proteins

1. estrogen and preg.
2. methadone/heroin
3. tranquiizers

8

what down regs. thyroid binding proteins

1. glucocorticoids
2. androgens
3. anti-cancer drugs

9

which thyroid hormone is more active and which is more common

T3 more potent, but T4 more volume

10

where does T3 come from

13% thyoid
87% is deiodinated T4

11

what removes iodine

deiodinase enzyme

12

how does T3/4 work

hydrophobic and passes through cell membrane to bind to receptor, which then bind to DNA

13

what are thyroid hormone receptors

a and B genes: TRa1, TRa2, TRB1 (everywhere)
TRB2 (brain)

14

effects of THs

1. Na/K ATP ase - Na out/ K in
2. increased O2
3. heat gen, sweating
4. weight loss
5. incr. resp
6. increased CV
7. increased metabolism

15

TH CNS effects

1. increased dev.
2. increased B-andrenergic receptors
3. faster reflexes

16

TH growth effects

1. pubertal growth spurt
2. allows GH function

17

what is TH feedback

-ve to pit and and hypo - TRH and TSH

18

what inhibs TRH

1. stress
2. TH

19

what inhibs TSH

1. dopamine,
2. somatostatin
3. glucocorticoids
4. TH

20

what happens in low iodine

can't make T3/4 so get high TRH and TSH and goiter

21

what are Sx of hypothyroidism

1. lethargy
2. fatigue
3. cold-intolerance
4. weakness
5. hairloss

22

what happens in graves disease

antibody produced that binds to TSH receptor and massive TH results

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