Adrenaline & Thyroxine

• What does adrenaline do?

  • Increases heart rate
  • Increases blood pressure
  • Increases blood flow to muscles
  • Increases blood sugar (glucose) levels by stimulating the liver to break glycogen down into glucose
• What does thyroxine do?

  Thyroxine has lots of roles in the body, including growth and development, but the main role is to increase your metabolic rate (the rate at which chemical reactions are taking place).
• Which gland produces thyroid stimulating hormone (TSH)?

  pituitary gland
• What happens if thyroxine levels are too low?

  The pituitary gland will release TSH. This then stimulates the thyroid gland to release more thyroxine. So thyroxine levels in the blood increase back up to normal.
• What happens if the thyroxine levels are too high?

  The thyroxine will inhibit the pituitary gland from producing TSH. Less TSH means that the thyroid gland won't release as much thyroxine. So thyroxine levels in the blood fall back to normal.
• The control of thyroxine levels by the hypothalamus and pituitary gland

  is an example of negative feedback.