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Flashcards in Thyroid Physiology Deck (27)
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1

The thyroid is supplied by the

superior and inferior thyroid artery and vein

2

__ is the biologically active thyroid hormone

T3

3

__ doesn't play a physiologic role but is a tumor marker for ___ thyroid cancer

Calcitonin; medullary

4

Thyroid increases basal ____ rate in all tissues except

metabolic; brain, testes, spleen

5

Thyroid effect on CV system

increases expression of alpha myosin heavy chains, which increases contractility and heart rate

6

Thyroid effect on heme

increases oxygen dissociation

7

Congenital hypothyroidism symptoms (aka cretinism)

severe mental retardation and dwarfism

8

T4 and T3 are made where

T4 exclusively in the thyroid gland, 80% of T3 converted from T4 outside the thyroid

9

_ has the major regulatory feedback on the hypothalamus and pituitary

T3

10

__ is required to synthesize thyroid hormone

iodine

11

This group needs more iodine and this other group need the most iodine

pregnant women, breast feeding women

12

Thyroglobulin is made by what and stored by

thyroid follicular epithelial cells; colloid

13

What is penderin

a iodine/cl transporter which move iodine to the membrane-colloid interface

14

Two reactions TPO catalyzes

Oxidation of Iodide to iodine and iodination of the thyroid hormone (adding iodine to it)

15

TPO gene stimulated by

TSH

16

Why do you have more T4 in the thyroid

it's made 10x faster than T3

17

T4, T3 and uncoupled DIT/MIT are bound to what in the colloid

Thyroglobulin

18

MIT and DIT combination is catalyzed by

TPO

19

What happens when the thyroid gland is stimulated by TSH

colloid is taken to the follicular cells by pinocytosis and there the thyroglobulin is cleaved off T3/T4 by proteases

20

Iodines are cleaved from unused DIT and MIT
by an enzyme called

thyroid deiodinase

21

Reverse T3 is ____ (activity)and made from ___

inactive; T4 iodine cleaved off the inner ring

22

Over 70% of T4/T3 are abound to

TBG

23

Half lives of T4/T3 and its significance

T4- 8 days, T3- one day, T4 is biologically very available

24

Estrogen and Hepatitis do what to TBG

increase it

25

How does pregnancy affect free T3 levels

doesn't affect em, achieves steady state

26

__ is the best measurement for thyroid function

TSH

27

Thyroid remains connected to foramen cecum by the __, which regresses at 8 weeks

thyroglossal duct