Negative feedback

• Negative feedback


  A type of control mechanism used in the process of homeostasis, the maintenance of a constant internal environment
• How negative feedback works

  1. Small change in one direction is detected by receptors

  2. Effectors work to reverse that change and restore conditions to normal level

  3. Constant cycle of sensing and triggering corrective mechanisms
• Negative feedback


  • Detects deviation from normal conditions
  • Triggers corrective mechanisms to restore normal conditions
  • Switches off corrective mechanisms when normal conditions are restored
• Thyroxine


  Hormone produced in the thyroid gland that regulates metabolic rate
• Thyroxine negative feedback loop


  1. Hypothalamus detects low thyroxine

  2. Hypothalamus signals pituitary to release TSH

  3. TSH signals thyroid to produce thyroxine

  4. Thyroxine levels increase

  5. Hypothalamus signals pituitary to stop TSH release

  6. Thyroid stops producing thyroxine

  7. Cycle repeats
• Adrenaline


  Hormone produced in the adrenal glands to prepare the body for fight-or-flight response to stress
• Effects of adrenaline


  • Increases cell respiration rate
  • Increases breathing and heart rate
  • Diverts blood away from digestive system to muscles
• Negative feedback is an important control mechanism used in homeostasis to maintain a constant internal environment
• Examples of negative feedback systems in the body include the regulation of thyroxine and adrenaline levels