Thyroid

Question 1

from where is the thyroid innervated?

Answer 1

the middle/inferior of cervical ganglia or SNS

Question 2

which artery vascularizes the thyroid?

Answer 2

the thyroid artery

Question 3

what is the functional unit of the thyroid?

Answer 3

thryoid follicle

Question 4

colloid

Answer 4

a thich fluid that fills follicular cells and stores TH. it contains iodinated thryoglobulin TG

Question 5

role of follicular cells

Answer 5

synthesize hormones

Question 6

thyroglobulin

Answer 6

large glycoprotein scaffold with tyrosines

Question 7

TH is made up of ____ and ____

Answer 7

iodide and tryosine

Question 8

what are the two TH’s

Answer 8

T3 and T4

Question 9

how is iodide moved around the body?

Answer 9

absorbed in GI tract
taken up by thryroid
removed by kidneys
transported by Na+/I- symporters

Question 10

how is TH made?

Answer 10

1. tyrosines are iodinated with thyroglobulin via thyroperoxidase(ox rxn).
2. Then these are coupled via thryoperoxidase to form T2 or T4
3. Epithelial cells endocytose colloid
4. endosomes fuse with lysosomes
5. lysosomes digest TG to release T3/T4
6. this free TH (T3 or T4) diffuses into the blood

Question 11

what is the main type of TH secreted?

Answer 11

T4

Question 12

which TH is active and why?

Answer 12

T3 is active, T4 is inactive due to its very high affinity for the TH receptor over T3

Question 13

circulating TH is bound to _____, or _____ or _____

Answer 13

1. thyroid binding globulin
2. transthyretin
3. albumin

Question 14

T4 is converted to T3 via ______

Answer 14

deiodinases

Question 15

rT3

Answer 15

reverse T3, this is inactive and is made by removing iodides from an inner ring

Question 16

which deiodinase is responsible for removing an iodide from an inner ring?

Answer 16

D3

Question 17

where is the TRH receptor?

Answer 17

cell membrane, gpcr

Question 18

what are 2 factors that regulate TH?

Answer 18

1. diet (high carbs)

2. conditions that increase body energy requirements

Question 19

how does TBG regulate TH?

Answer 19

They are directly correlated, as TBG increases, so does TH

Question 20

wolff-chaikoff effect

Answer 20

the autoregulatory inhibition of the organification of iodine as there is an increase in circulating iodine. helps regulate T3/T4 production

Question 21

factors that contribute to TH synthesis

Answer 21

nutrients such as

iron, iodine, tyrosine, zince, and vitamins

Question 22

factors that inhibit TH synthesis

Answer 22

stress, infection, trauma, fluroide, toxins, diseases

Question 23

how is transcription initiated by TH?

Answer 23

TH passes through the transporters and enters the nucleus where it binds to factors on TRE sequence of DNA.

Question 24

what are the effects of TH?

Answer 24

1. increase metabolism
2. burn calories
3. heat production
4. metabolize substrates