The Thyroid Gland

Question 1

Thyroid gland sit at the base of the …… across the ………

Answer 1

larynx

trachea

Question 2

the thyroid synthesises hormones. There are two physiologically active forms:

Answer 2

T3 (triiodothyronine)

T4 (thyroxine)

Question 3

two cells types found in the thyroid gland

Answer 3

C (clear) cells

follicular cells

Question 4

c (clear) cells secrete

Answer 4

calcitonin (Ca2+ regulating hormone)

Question 5

Follicular cells support ………. ………. synthesis and surround the …… ………..

Answer 5

thyroid hormone

hollow follicles

Question 6

thyroid follicles are spherical structures whose walls are made of

Answer 6

follicular cells

Question 7

the centre of follicle is filled with

Answer 7

colloid

Question 8

colloid contains 2-3 months supply of

Answer 8

TH

Question 9

follicular cells manufacture the enzymes that make thyroid hormones as well as….

Answer 9

thyroglobulin

Question 10

thyroglobulin is a large protein that is rich in ….

Answer 10

tyrosine residues

Question 11

The enzymes and thyroglobulin are packages into vesicles and exported from the …. cells into the …….

Answer 11

follicular

colloid

Question 12

follicular cells also have a role in concentrating ……..from the plasma and transporting it into the …….. where it combines with ………. residues to from the thyroid hormones.

Answer 12

iodide

colloid

tyrosine

Question 13

both tyrosine and iodide are derived from the ………

Answer 13

diet

Question 14

Iodide enters the follicular cells from the plasma via a ………/ ……. transporter (symport)

Answer 14

sodium/iodine

Na+/I-

Question 15

The addition of one iodine to tyrosine gives

Answer 15

MIT

monoidotyrosine

Question 16

The addition of one iodine to tyrosine gives

Answer 16

MIT

monoidotyrosine

Question 17

The addition of two iodine to tyrosine gives

Answer 17

DIT

diiodotyrosine

Question 18

MIT + DIT –>

Answer 18

T3

Question 19

DIT + DIT –>

Answer 19

T4

Question 20

in response to …….., portions of the colloid are taken back up in to the follicular cell by endocytosis.

Answer 20

TSH

Question 21

Both T3 and T4 are ……… ……..and so pass across the follicular cell membrane into the plasma where they bind to plasma proteins, mainly ……….-………… ……….

Answer 21

lipid soluble

thyroxine-binding globulin

Question 22

Both T3 and T4 circulate in the …………

Answer 22

plasma

Question 23

in absence of TSH, thyroid hormones are stored in the ……….

Answer 23

colloid

Question 24

Most TH circulates in the form of protein bound ….. (~100nmoles/l)

Answer 24

T4

Question 25

The TH receptor has a much higher affinity for ..... than ...... making ...... 3-5 times more physiologically active than .....

Answer 25

T3 T4 T3 T4

Question 26

Around half the T4 is deiodinated in .........., the remaining fraction being deiodinated inside .......cells.

Answer 26

plasma target

Question 27

The level of ....... activity can be altered at different times in different tissues to suit demand.

Answer 27

deiodinase

Question 28

what do glucocorticoids inhibit?

Answer 28

TSH and conversion of T4 to T3

Question 29

somatostatins inhibit | as well as GH

Answer 29

TSH

Question 30

TH bind to nuclear receptors in target cells, where they change transcription and translation to alter ......... .............

Answer 30

protein synthesis

Question 31

TH raises metabolic ..... and promotes ......

Answer 31

rate thermogenesis

Question 32

What does TH do to hepatic gluconeogenesis?

Answer 32

increases it

Question 33

TH allows for a net increase in what two processes?

Answer 33

lipolysis proteolysis

Question 34

TH is essential for growth as it simtulates what?

Answer 34

GH receptor expression

Question 35

Hyperthyroidism causes:

Answer 35

Graves diseases Thyroid adenoma

Question 36

Graves disease is characterized by antibodies that bind and mimic ....... and continually activate the ...... ......

Answer 36

TSH thyroid gland

Question 37

In graves disease, increased release of TH switches off....... released from the anterior pituitary therefore - TSH in plasma is .....

Answer 37

TSH low

Question 38

hyperthyroidism signs

Answer 38

weight loss/ heat tolerance muscle weakness hyper excitable reflexes increased HR/ contractile force

Question 39

Hypothyroidism causes

Answer 39

hashimotos disease Iodine deficiency idiopathic (thyroiditis)

Question 40

hashimoto's disease

Answer 40

autoimmune attack of the thyroid gland

Question 41

Hypothyroidism signs

Answer 41

weight gain/ cold tolerance brittle nails/ thin skin slow speech/reflexes / fatigue slow heart rate/ weaker pulse

Question 42

Goitre formation may be caused by increased trophic action of ........ on thyroid ....... cells (hypothyroidism) or over-activity as a result of autoimmune disease (....... Disease)

Answer 42

TSH follicular Graves