Negative feedback

• Thyroxine

  Hormone released by the thyroid gland
• Adrenaline

  Hormone released by the adrenal glands during times of fear or stress
• Effects of adrenaline

  1. Increases heart rate

  2. Delivers more oxygen and glucose to brain and muscles
• Fight-or-flight


  The body's response to prepare to either fight or run away
• Thyroxine

  • Stimulates the body's basal metabolic rate
  • Plays an important role in growth and development
• Negative feedback control of thyroxine levels

  1. Brain monitors thyroxine level

  2. If thyroxine level falls, pituitary gland releases TSH

  3. TSH triggers thyroid gland to release more thyroxine

  4. Increased thyroxine level detected by brain

  5. Brain prevents pituitary gland from releasing TSH

  6. Thyroid gland releases less thyroxine
• Negative feedback cycles exist in the human body for the control of blood glucose and the menstrual cycle