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Flashcards in Thyroid Gland Deck (69)
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1

The thyroid gland produces ___ and ___.

T3; T4

2

Parafollicular C cells secrete ____.

calcitonin

3

T3 and T4 are synthesized by the _____ ____ cells.

follicular epitheliall

4

____ is composed of newly synthesized thyroid hormones attached to thyroglobulin.

Colloid

5

Thyroid follicle cells secrete ___ micrograms of new hormone/day.

60

6

__ is the major secretory product of the thyroid gland.

T4

7

Most circulating T3 is due to ____ ____ of T4.

peripheral conversion

8

Fasting, medical and surgical stress, and catabolic diseases causes a ____ in the conversion of T4 to T3.

reduction

9

Mutation in the ___ gene causes defects in iodide transport across the apical membrane. Mutations in this gene also affects the cochlea where it causes sensorineural hearing loss.

Pendrin

10

Patients with Pendred syndrome usually have _____ with goiter.

hypothyroidism

11

Deficiency of ____ mimics dietary iodide deficiency.

deiodinase

12

When the availability of iodide is restricted, the formation of __ is favored.

T3

13

High levels of iodide ___ organification and synthesis of thyroid hormones -- the Wolff-Chaikoff effect.

inhibit

14

___ inhibits peroxidase, causing high levels of iodide, inhibiting synthesis of thyroid hormones.

PTU

15

PTU is an effective treatment for ____.

hyperthyroidism

16

17

Do most thyroid hormones circulate in the blood stream bound to plasma proteins or free?

bound to plasma proteins

18

What are the main binding proteins for T3 and T4?

Thyroxine-binding protein (TBG), transthyretin (TTR), and albumin

19

T4's half life is _ days. T3's half life is _ days.

6; 1

20

Circulating levels of ___ can be indirectly assessed with T3 resin uptake test.

TBG

21

High TBG results in __ T4 and __ T3 resin uptake.

high; low

22

Low TBG results in __ T4 and __ T3 resin uptake.

low; high

23

Hepatic failure results in __ TBG and __ T3 resin uptake.

low; high

24

Pregnancy results in __ TBG and __ T3 resin uptake.

high; low

25

Pregnancy results in __ TBG levels, __ bound T3 and T4, and ___ free T3 and T4.

high; high; low

26

The high total levels of T3 and T4, but normal levels of free, physiologically active thyroid hormones results in a state where the person is said to be ____ ____.

Clinically euthyroid

27

Hyperthyroidism will have __ T4 and ___ T3 resin uptake.

high; high

28

Hypothyroidism will have __ T4 and __ T3 resin uptake.

low; low

29

Describe the HPT axis.

TRH>TSH>T3&T4.

T3&T4 inhibit TSH and TRH secretion.

30

___ regulates the growth of the thyroid gland (trophic effect) and the secretion of thyroid hormones.

TSH