Regulation of Thyroid Hormone Synthesis Flashcards Preview

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Flashcards in Regulation of Thyroid Hormone Synthesis Deck (24):
1

Thyroid hormone is a _________-derived hormone.

tyrosine

2

The skeleton of thyroid hormone is ___________.

thyronine

3

The thyroid hormone is made hydrophobic by ___________.

its ether linkage

4

The full name of T4 is ________________.

3,5,3',5'–tetraiodothyronine (also called thyroxine)

5

The full name of T3 is _________________.

3,5,3'–triiodothyronine

6

The thyroid has a copious blood supply. One of the reasons this is thought to be so is _____________.

that iodide is a trace element in water, and in the natural world we would need to absorb as much iodide from the water as possible

7

How is iodide absorbed by thyroid follicular cells?

By a sodium/iodide symporter (the intracellular sodium is then pumped back out through a Na/K antiporter)

8

The thyroid follicular cells secretes ____________ into the lumen of the thyroid.

thyroglobulin

9

Thyroglobulin is used entirely within _____________.

the thyroid gland

10

Each thyroglobulin protein contains approximately ____________ tyrosine residues that can be used to make T4.

20 (although there are many more tyrosine residues)

11

Thyroglobulin is made in a non-iodinated form that then gets _________________.

secreted by the thyroid follicular epithelium into the follicular colloid

12

Thyroglobulin gets iodinated in the ______________.

colloid and then taken up by endocytosis back into the thyroid follicular epithelium

13

T3 and T4 bind _______________.

nuclear receptors

14

Low levels of T3 induce a metabolic shift to ____________.

anabolism

15

High levels of T3 induce a metabolic shift to ______________.

catabolism

16

High levels of thyroid hormone stimulate which adrenergic receptor?

Beta-1

17

TSH regulates which points of thyroid production and release?

- Growth of follicular cells
- Transporters
- Thyroperoxidase
- Thyroglobulin
- Organification of iodide (putting free iodide onto protein)
- Endocytosis of thyroglobulin from the colloid

18

The primary constituent of the colloid is _______________.

thyroglobulin

19

Where is thyroperoxidase?

In the colloid, bound to the membrane

20

What are DIT and MIT?

Diiodotyrosine and monoiodotyrosine – these couple to form triiodothyronine

21

Where are T4 and T3 cleaved from thyroglobulin?

In follicular lysosomes

22

_____________ has a longer half-life.

T4 (another reason thyroxine is given pharmaceutically)

23

Why does thyrotoxicity mimic catecholamine overdose?

Because thyroid hormone potentiates the effects of catecholamines

24

List five effects of thyroid hormone.

- Increased basal metabolic rate
- Potentiation of catecholamine effects
- Promotes linear growth throughout childhood
- Promotes brain development throughout childhood
- Promotes anabolic effect at low doses and catabolic effect at high doses

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