B3.5 Adrenaline and Thyroxine

• Where are the adrenal glands located?

  On top of the kidneys
• What hormone is produced by the adrenal glands?

  Adrenaline
• When is adrenaline produced?

  During the 'fight or flight' response
• What does adrenaline prepare the body for?

  Activity during stress or danger
• What are the main effects of adrenaline on the body?

  • Increases heart rate
  • Increases blood pressure
  • Increases blood flow to muscles
  • Increases blood sugar levels
• What hormone is produced by the thyroid gland?

  Thyroxine
• What is the main role of thyroxine in the body?

  To increase metabolic rate
• How is the production of thyroxine regulated?

  By Thyroid Stimulating Hormone (TSH)
• What does the pituitary gland produce to stimulate thyroxine production?

  Thyroid Stimulating Hormone (TSH)
• What happens if thyroxine levels are too low?

  TSH is released to increase thyroxine
• What happens if thyroxine levels are too high?

  Thyroxine inhibits TSH production
• What is the negative feedback mechanism in thyroxine regulation?

  • High thyroxine levels inhibit TSH release
  • Low thyroxine levels stimulate TSH release
  • Maintains stable thyroxine levels in blood
• How does the hypothalamus and pituitary gland control thyroxine levels?

  Through negative feedback mechanisms
• What is the effect of high thyroxine levels on TSH release?

  It inhibits TSH release
• What is the effect of low thyroxine levels on TSH release?

  It stimulates TSH release
• Which organ is adrenaline released from?

  Adrenal gland
• What effect does adrenaline have on heart rate?


  It increases heart rate
• When is adrenaline released?


  When you're scared
• Adrenaline causes changes in the body to prepare for a ‘fight or flight’ response.

  Describe 3 of these changes. 

  • Increase heart rate
  • Increase blood pressure
  • Increase blood flow to muscles 
  • Increases blood sugar (glucose) levels
• Adrenaline causes the conversion of which substances? 

  Glycogen ➔ glucose
• Which organ is thyroxine released from?

  Thyroid gland
• What is the main role of thyroxine?

  To increase your metabolic rate
• Which organ is TSH released from?

  Pituitary gland
• The hormone TSH is involved in the regulation of thyroxine levels. 

  What does TSH stand for?

  Thyroid stimulating hormone
• Does thyroxine stimulate or inhibit the pituitary gland from releasing TSH?

  Inhibit
• Does TSH stimulate or inhibit the thyroid gland from releasing thyroxine?


  Stimulate 
• Which type of feedback is involved in the regulation of thyroxine levels?

  Negative feedback
• Describe what will happen when thyroxine levels are too high

  • Thyroxine inhibits the pituitary gland from releasing TSH.
  • Less TSH means the thyroid gland won't release as much thyroxine. 
  • Thyroxine levels fall back to normal over time.
  • This is an example of Negative feedback