7.3 - **Higher Only** Thyroxine and Metabolic Rate

Question 1

What does thyroxine regulate?

Answer 1

Thyroxine regulates metabolic rate and is important in growth and development.

Question 2

What hormone is stimulated by low levels of thyroxine?

Answer 2

Low levels of thyroxine stimulate the production of TRH in the hypothalamus.

Question 3

What does TRH cause the release of?

Answer 3

TRH causes the release of TSH from the pituitary gland.

Question 4

What is the role of TSH?

Answer 4

TSH acts on the thyroid to produce thyroxine.

Question 5

What happens when thyroxine levels reach normal levels?

Answer 5

Thyroxine inhibits the release of TRH, stopping the production of TSH.

Question 6

How are thyroxine levels controlled?

Answer 6

Thyroxine levels are controlled by negative feedback.

Question 7

What occurs when thyroxine levels increase?

Answer 7

Increased thyroxine levels are detected by receptors in the brain, inhibiting the release of TSH.

Question 8

What is the effect of inhibiting TSH release?

Answer 8

Inhibiting TSH release leads to the inhibition of thyroxine release, causing thyroxine levels to fall.