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1

Thyroid gland

Largest endocrine gland, has two lobes, located anterior on the neck underneath the larynx of the voice box, and produce 2 hormone

2

The two lobes of the thyroid gland is connected by a narrow tissue called

Isthmus

3

The two hormone made by the endocrine gland

T3 triiodothyronine and T4 tetraiodothyronine(thyroxin)

4

Between T3 and T4 which is produced more

93% of the hormones made are T4 but later converted to T3

5

The thyroid gland controls

BMR basal metabolic rate

6

Thyroid stimulating hormone

TSH is produce in the pituitary gland and controls thyroid directly.

7

TSH is produced

In the adenohypophyseal of the pituitary gland

8

Para follicular cells

Release thyrocalcitonin that lowers ca level in the blood

9

Follicular cells

Synthesizes an inactive hormone that is a glycoproteins (thyroglobulin) with mainly tyrosine residue

10

Thyroglobulin

A precursor to the iodinated T3 and T4 protein

11

Parathyroid glands are also found in the

Thyroid glands with two in each lobe making 4 parathyroid

12

The hormone produced by the parathyroid glands and it function

PTH to control ca levels

13

Hypothyroidism

Caused by not enough iodine, it is acquired through diet, only 1/5 of the iodine is absorbed and the rest is excreted through the kidneys

14

TSH is the driving force of

Iodide trapping of the thyroid follicular cells

15

During iodide trapping the cell

Becomes 30 times more concentrated with I- in the cytoplasm

16

Before organification can occur

Thyroglobulin protein are synthesize they brought to lumen side of cell by exocytosis

17

Organification is the

Adding of iodine to thyroglobulin at the apex of the cell

18

After organification

The compound is taken up by the cell by endocytosis and goes into the lysosomes of the cell to be cleaved furthermore changing them to an active T3 or T4 hormone

19

T3 and T4 can diffuse through the membrane into the bloodstream because they are

Fat soluble

20

After diffusing through the membrane T3 and T4

They bind to the protein thyroxine

21

Thyroxine -binding protein

A protein that binds to T3 and T4 in the bloodstream to inactivate them. This protein is synthesize in the liver

22

NIS (sodium iodide symportor)..

A carrier protein that utilizes secondary active transport to move Na+ and 1I- into the cell

23

Pendrin

A counter proter that moves one cl into the cell and one I - out of the cell at the lumen side of the thyroid follicle cell

24

Iodanase

An enzyme that attaches iodide to the residues of thyroglobulin proteins will eventually become either T3 and T4. It changes T4 to T3

25

Organification

Attachment of iodide to the thyroglobulin protein

26

Retinoids

T3 goes into the nucleus and it binds to retnoid x

27

Retnoid x

A heterdimer protein that is transcription factor. It make the cell produce more proteins. Retnoid x has a specific Binding site on the DNA

28

Response element ( thyroid hormone response element )

Retnoid x has specific binding site on the DNA

29

What vitamins also binds to retnoid x

Vitamin D

30

Non genomic effects of T3

Increase basal metabolic rate which keeps you alert , causes an increase in cellular respiration, increase protein synthesis and catabolism, increase the number of mitochondria , increase carbohydrate metabolism, it can have an have an opposite effect if the person is deficient in iodine , therefore making them lethargic depressed, low heart rate, and no ambition to do anything