Hormones And Metabolic Rate

Question 1

What is metabolic rate?

Answer 1

The rate at which the energy stores in your food is transferred by all the reactions that take place in your body to keep you alive

Question 2

What do the adrenal glands release?

Answer 2

Adrenalin

Question 3

When might Adrenalin be secreted?

Answer 3

During frightening or exciting situations, due to an increase in impulses from neurones reaching the adrenal glands from the spinal cord

Question 4

What is adrenalin’s effect on the heart? What does it make happen to the heart? The

Answer 4

Heart cells contract MORE RAPIDLY (increase heart rate) and MORE STRONGLY (increase blood pressure)

Question 5

What is adrenalin’s effect on the liver?

Answer 5

Cells change from glycogen to glucose quicker

More glucose is released into the blood, increasing blood sugar concentration

Question 6

How does Adrenalin affect blood vessels?

Answer 6

Leading to the targeted muscles - blood vessels widen, increasing blood flow to those targeted muscles
Other organ’s blood vessels - narrow, reducing blood flow and increasing blood pressure

Question 7

What is negative feedback?

Answer 7

A control mechanism that reacts to a change on a condition by trying to bring the condition down to a normal level

Question 8

Explain how changes caused by Adrenalin prepare the body for ‘fight or flight’

Answer 8

By increasing blood flow to targeted organs + with heart rate increasing, the body can act quickly on whether to run away from danger or fight it
- Increased heart rate, blood pressure, blood sugar levels and blood flow also cause this ‘fight or flight’ instinct

Question 9

Describe the negative feedback diagram for thyroxine

Answer 9

Hypothalamus 
⬇️ TRH
Pituitary gland
⬇️ TSH
Thyroid gland
⬇️Thyroxine
Other target organs 
(When lower concentration than normal,the hypothalamus is stimulated again)
(When higher than normal, signals are sent yo the pituitary and hypothalamus to make them less active and consequently, less thyroxine is produced)

Question 10

How does thyroxine control metabolic rate as a negative feedback?

Answer 10

• Low Levels of thyroxine stimulates the production of TRH in the hypothalamus
• This causes the release of TSH from the pituitary gland
• TSH acts on the thyroid to produce thyroxine
• When thyroxine levels aren’t normal, thyroxine inhibits the release of TRH and the production of TSH
• This keeps the metabolic rate steady