Thyroid gland

Question 1

What does the hypothalamus release?

Answer 1

TRH - thyrotropin releasing hormone

Question 2

What does the anterior pituitary release?

Answer 2

TSH - thyroid stimulating hormone

Question 3

How does the TRH travel to the pituitary?

Answer 3

Vua the hypophyseal portal system

Question 4

What does TSH do?

Answer 4

Only acts on thyroid once released from the anterior pituitary

Increases trapping and iodination of tyrosine to form more T3 and T4

Question 5

What is the name for T3?

Answer 5

Triiodothyronine

Question 6

What is the name for T4?

Answer 6

Thyroxine

Question 7

What is the negative feedback loop in thyroid hormone synthesis?

Answer 7

When T3 and T4 concentrations are low, production of TSH is increased

Affects hypothalamus and anterior pituitary

Question 8

How are thyroid hormones synthesised?

Answer 8

1. TSH released from anterior pituitary stimulates thyroglobulin production in thyroid gland
2. The thyroglobulin is transported into a colloid
3. Iodide is transported into the colloid via transporter Pendrin
4. Iodination of thyroglobulin is catalysed by TPO
5. Proteolysis stimulated by TSH of iodinated thyroglobulin releases free T3 and T4

Question 9

What is a colloid?

Answer 9

A liquid shared by many thyroidal cells within a thyroid follicle

Question 10

What does TPO stand for?

Answer 10

Thyroid Peroxidase

Question 11

What is Thyroglobulin?

Answer 11

A tyrosine-rich protein