Adrenaline and Thyroxine

• Adrenaline is a hormone produced by the adrenal glands (which sit just on top of the kidneys).
• Adrenaline is produced during the 'fight or flight' response, when you get scared, stressed, or need to exercise. It prepares the body for activity.
• Adrenaline increases:

  • Heart rate
  • Blood Pressure
  • Blood flow to muscles
  • Blood sugar by stimulating the liver to break down glycogen into glucose
• Thyroxine is produced by the thyroid gland, which is found in the neck.
• 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).
• The pituitary gland produces Thyroid Stimulating Hormone (TSH), which stimulates the thyroid gland to produce thyroxine.

  Thyroxine then inhibits the production of TSH from the pituitary gland.
• If thyroxine levels are too low - the pituitary gland will release TSH. This then stimulates the thyroid gland to release more thyroxine
• If 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.
• The control of thyroxine levels by the hypothalamus and pituitary gland is an example of negative feedback. If levels of thyroxine rise too high, it will bring about changes to lower the levels, and if they fall too low, it brings about changes to raise them back up.
• Thyroxine increases the metabolic rate
• TSH is released from the pituitary gland