Negative Feedback

• What is negative feedback?

  Negative feedback is a control system that maintains a stable internal environment by reversing changes in the body. When a condition moves too high or too low, the body responds to bring it back to normal
• Why does the body use negative feedback?

  Negative feedback keeps conditions in the body stable (homeostasis), preventing dangerous fluctuations in temperature, blood sugar, and hormone levels.
• What are the steps in a negative feedback loop?

  1. A change is detected (e.g., temperature rises).
  2. The nervous system or endocrine system responds.
  3. A hormone or nerve signal triggers a corrective action.
  4. The condition returns to normal, and the response stops.
• How does negative feedback control blood glucose levels?

  1. High blood sugar → The pancreas releases insulin → Glucose is absorbed → Blood sugar returns to normal.
  2. Low blood sugar → The pancreas releases glucagon → Glycogen is broken down into glucose → Blood sugar returns to normal.
• How does negative feedback regulate body temperature?

  1. Too hot: Blood vessels dilate (vasodilation), sweating increases, and heat is lost.
  2. Too cold: Blood vessels constrict (vasoconstriction), shivering increases, and heat is retained.
• How does negative feedback regulate thyroxine levels?

  • Low thyroxine levels → The pituitary gland releases TSH → The thyroid gland produces more thyroxine → Levels return to normal.
  • High thyroxine levels → The pituitary gland stops releasing TSH → Thyroxine levels fall.
• What are the key characteristics of negative feedback?

  • Automatic response – The body corrects itself without conscious control.
  • Involves hormones or nerves – Uses the nervous and endocrine systems.
  • Maintains homeostasis – Keeps the internal environment stable.