Thyroid gland

Question 1

Vertebral levels of the thyroid

Answer 1

C5 to T1

Question 2

Tracheal rings which the thyroid isthmus covers

Answer 2

Tracheal rings 2 and 3

Question 3

At which week does the thyroid begin to migrate from the floor of the foregut

Answer 3

3-4 weeks

Question 4

The site from which the thyroid originated persists as the ______

Answer 4

foramen cecum

Question 5

At which week does the thyroid begin secreting hormone

Answer 5

18th week

Question 6

Where would a thyroglossal cyst be located

Answer 6

In the midline of the neck

Question 7

Where would a branchial cyst be located

Answer 7

Anterior to the sternocleidomastoid

Question 8

Where would a lingual thyroid be seen

Answer 8

At the back of the tongue

Question 9

TSH stimulates which cells

Answer 9

Thyroid follicular cells

Question 10

TSH stimulates follicular cells by which second messenger system

Answer 10

Gs

Question 11

TSH stimulates the production of which protein

Answer 11

thyroglobulin

Question 12

Functions of thyroid peroxidase

Answer 12

1. oxidation of iodide to iodine
2. Addition of iodine to tyrosine residues on thyroglobin
3. coupling of DIT and MIT

Question 13

T3 and T4 can only be transported in the blood bound to which molecule

Answer 13

Thyroxine binding globulin

Question 14

Where us thyroxine globulin synthesized and what is its function

Answer 14

TBG is synthesized in the liver and is needed to transport T3 and T4 in the blood

Question 15

Which enzyme is needed to convert T4 to T3

Answer 15

5’ iodinase

Question 16

During starvation there is an upregulation of which thyroid hormone

Answer 16

rT3

Question 17

Which transporter is need to for enter of iodide into the thyroid follicular cells

Answer 17

sodium-iodide symporter

Question 18

Apart from TBG which other molecules can T3 and T4 be bound to to be transporter

Answer 18

Albumin and pre-albumin

Question 19

Which thyroid hormone has a longer half life

Answer 19

T4

Question 20

Which thyroid hormone is more biologically active

Answer 20

T3

Question 21

How is the autoregulation of thyroid hormone production done

Answer 21

low iodide levels increase iodine transport into follicular cells while high iodide levels decrease iodine transport into follicular cells

Question 22

In Primary hypothyroidism what happens to levels of :

T4
TSH
TRH

Answer 22

T4 - decreased
TSH - inceased
TRH - increased

Question 23

In Pituitary hypothyroidism what happens to levels of :

T4
TSH
TRH

Answer 23

T4 - decreased
TSH - deceased
TRH - increased

Question 24

In hypothalamic hypothyroidism what happens to levels of :

T4
TSH
TRH

Answer 24

T4 - decreased
TSH - deceased
TRH - decreased

Question 25

In pituitary hyperthyroidism what happens to levels of : T4 TSH TRH

Answer 25

T4 - increased TSH - inceased TRH - decreased

Question 26

In Graves' disease what happens to levels of : T4 TSH TRH

Answer 26

T4 - increased TSH - deceased TRH - decreased

Question 27

Any condition that increases body energy requirements ______ (stimulates/inhibits) the hypothalamus to produce TRH

Answer 27

Stimulates the hypothalamus to produce TRH

Question 28

Effects of Thyroid hormone

Answer 28

- increase basal metabolic rates - increased HR and contractility by increasing beta 1 receptors - increase RR - increase renal blood flow and GFR - increased O2 dissociation from Hb - ovulation, maintenance of pregnancy, spermatogenesis, menstruation - brain maturation - CNS development ad emotion tone - increase glucose absorption in gut - growth of bones - protein breakdown in muscles

Question 29

True or false: Goiter can be caused only by hyperthyroisism

Answer 29

False. Goiter can be caused by both hyperthyroidism and hypothyroidism