Topic 5c- Thyroxine and adrenaline

Question 1

What gland is thyroxine released by?

Answer 1

Thyroid gland

Question 2

What is thyroxine released in response to?

Answer 2

TSH (Thyroid Stimulating Hormone) → produced in the pituitary gland

Question 3

Describe what happens when the level of thyroxine in the blood is higher than normal

Answer 3

• When the level of thyroxine in the blood is higher than normal, the secretion of TSH from the pituitary gland is inhibited.
• This therefore reduces the amount of thyroxine released from the thyroid gand, so the level in the blood falls back to normal.

Question 4

Describe what happens when thyroxine levels in the blood are lower than normal

Answer 4

• When the level of thyroxine in the blood is lower than normal, the secretion of TSH from the pituitary gland is stimulated.
• This increases the amount of hydroxine released from the thyroid gland, so the level in the blood rises back towards normal.

Question 5

What gland releases adrenaline?

Answer 5

adrenal glands

Question 6

Why is adrenaine released?

Answer 6

• In response to stressful or scary situations

Question 7

What is the process that stimulates the release of adrenaline?

Answer 7

• Brain detects fear or stress
• Brain sends nerve impulses to the adrenal glands
• Adrenal glands respond by secreting adrenaline
• Adrenaline gets the body ready for ‘fight or flight’ response by triggering mechanisms that increase the supply of oxygen and glucose to the cells in the brain and muslces
• An example of this being that it increases heart rate.

Question 8

What are the roles of thyroxine in the body?

Answer 8

• Regulating the basal metabolic rate
• Stimulating protein synthesis for growth and development