Thyroid Physiology

Question 1

List the main thyroid hormones

Answer 1

Thyroxine (T4)
Triiodothyronine (T3)
Calcitonin

Question 2

What chemical is the main “fuel source” of the thyroid?

Answer 2

Iodine

Question 3

What happens to iodine once it is taken up by the follicle cells of the thyroid?

Answer 3

Combines with tyrosine residues on thyroglobulin to form MIT or DIT

Question 4

Outline the composition of T3

Answer 4

MIT + DIT

Question 5

Outline the composition of T4

Answer 5

DIT + DIT

Question 6

T3 is the more abundant thyroid hormone. True/False?

Answer 6

False

T4 makes up 90% of thyroid hormones

Question 7

Is T3 or T4 more biologically active?

Answer 7

T3

Question 8

T4 is converted to T3 by liver/kidney. True/False?

Answer 8

True

Question 9

The unbound form of thyroid hormone is biologically inactive. True/False?

Answer 9

False

Unbound is active!

Question 10

What are the 2 main types of cell found in the thyroid?

Answer 10

Follicular cells

Parafollicular C cells

Question 11

What is stored in the colloid of the thyroid?

Answer 11

Thyroglobulin

Question 12

What do follicular cells secrete?

Answer 12

Thyroglobulin

Question 13

T3 and T4 are hydrophobic. True/False?

Answer 13

True