negative feedback

• • adrenaline is released by adrenal glands in times of fear and stress
  • adrenaline increases heart rate and boosts delivery of oxygen and glucose to brain and muscles
• • thyroxine is produced by thyroid gland
  • thyroxine stimulates basal metabolic rate
  • thyroxine stimulates protein synthesis for growth and development
• • thyroxine is released in response to thyroid stimulating hormone (TSH) which is released by pituitary gland
• • high levels of thyroxine in blood inhibits release of TSH from pituitary gland
  • reduces amount of thyroxine released from thyroid
  • low levels of thyroxine in blood stimulates release of TSH from pituitary gland
  • increases amount of thyroxine released from thyroid