Thyroid Gland

Question 1

What type of transport is used to transport iodide into the thyroid gland cell?

Answer 1

Active transport

Question 2

What occurs once iodide is actively transported into cells?

Answer 2

Iodide is oxidised to iodine

Question 3

Monoiodotyrosine (MIT) and diodotyrosine (DIT) together make up which form of thyroid hormone?

Answer 3

Triiodothyronine (T3)

Question 4

Two diodotyrosines (DIT) together make up which form of thyroglobulin?

Answer 4

Thyroxine (T4)

Question 5

How much of T3 in the plasma is secreted by the thyroid?

Answer 5

20%

Question 6

What molecules act on the pituitary gland to inhibit thyroid hormone secretion?

Answer 6

Corticosteroids, dopamine.

Question 7

List the effects of T3 and T4 on the liver.

Answer 7

Increased gluconeogenesis, glycogenolysis and blood glucose.

Question 8

List the effects of T3 and T4 on the GI tract.

Answer 8

Increased CHO absorption

Question 9

List the effects of T3 and T4 on the muscles.

Answer 9

Increased protein synthesis and even more increased protein degradation.

Question 10

List the effects of T3 and T4 on adipose tissue.

Answer 10

Increased lipogenesis and even more increased lipolysis.

Question 11

What factors increase TRH secretion?

Answer 11

Cold, acute psychosis, circadian rhythm, decreased T3 and T4..

Question 12

What factors decreases TRH secretion?

Answer 12

Severe stress, increased T3 and T4.

Question 13

What are the secretion patterns of T3 and T4 like?

Answer 13

Pulsatile for T4 (peaks in morning) and diurnal for T3.

Question 14

What happens once T4 and T3 enter the cell?

Answer 14

All T4 is converted to T3 and T3 enters the nucleus.

Question 15

What is the effect of thyroid hormone on growth?

Answer 15

Growth formation, bone maturation.

Question 16

What is the effect of thyroid hormone on the CNS?

Answer 16

Maturation of the CNS

Question 17

What is the effect of thyroid hormone on BMR?

Answer 17

Increase sodium-potassium pump activity, oxygen consumption, heat production and BMR.

Question 18

What is the effect of thyroid hormone on metabolism?

Answer 18

Increased glucose absorption, glycogenolysis, gluconeogenesis, lipolysis, net protein catabolism.

Question 19

What is the effect of thyroid hormone on the CVS?

Answer 19

Increased cardiac output through potentiation of the effects of catecholdamines.

Question 20

Why is serum TSH measured?

Answer 20

To determine whether there is a primary or secondary thyroid defect.

Question 21

In immunoassays are total TSH or free TSH of clinical significance?

Answer 21

Free TSH as free TSH has biological activity.

Question 22

What are radioiodine studies used for?

Answer 22

To determine the thyroid areas with increased or decreased function.

Question 23

What is indicative of primary hyperthyroidism?

Answer 23

Low TSH and high T3/T4.

Question 24

What is indicative of secondary hyperthyroidism?

Answer 24

High TSH and high T3/T4.

Question 25

What is indicative of primary hypothyroidism?

Answer 25

High TSH and low T3/T4.

Question 26

What is indicative of secondary hypothyroidism?

Answer 26

Low TSH and low T3/T4.

Question 27

In radioiodine studies what are cold and hot nodes?

Answer 27

Cold nodes- low activity

Hot nodes- high activity.

Question 28

What autoimmune disease causes hypothyroidism?

Answer 28

Hashimotos disease- production of antibodies against thyroglobulin.

Question 29

What autoimmune disease causes hyperthyroidism?

Answer 29

Graves disease- production of molecules that mimic T3/T4.