Principles of Negative Feedback Mechanisms

Chapter: Principles of Negative Feedback Mechanisms

  • Negative feedback mechanisms are biological processes that help to maintain a stable internal environment or ‘homeostasis’.
  • This process works to counteract changes in the body. When a change is detected by a sensor, a response is then generated to restore the balance.
  • Examples of negative feedback mechanisms in the body include blood glucose regulation and body temperature control.
  • These mechanisms involve a series of steps often referred to as a feedback loop. This comprises a receptor, a control center and an effector.
  • The receptor is the sensor which recognises the change in condition. This could be heat-sensitive cells in the skin when considering body temperature, or cells in the pancreas that detect glucose levels when considering blood glucose regulation.
  • The control center is the part of the body that processes the information provided by the receptors and sends a message to the effectors to react to the change. The hypothalamus in the brain often plays this role.
  • The effector is the part of the body that carries out the response in order to counteract the change. For instance, when blood glucose levels are high, insulin is released from the pancreas to help the cells take in glucose and reduce the blood glucose level.
  • These feedback loops are self-regulating, meaning once the initial change has been reversed, the feedback mechanism will stop the corrective measures.
  • It’s important to note that negative feedback systems don’t always produce a perfect balance, but bring about a level that keeps the internal environment within certain boundary limits.
  • If a negative feedback system fails and the body’s balance is not restored, it could result in disease or health issues. For example, if the body cannot regulate glucose levels appropriately, it could lead to diabetes.
  • Key concept to understand: negative feedback systems work towards maintaining stability while positive feedback mechanisms amplify or increase the occurrence of events.

Revision Questions:

  1. Give an explanation of how body temperature is controlled using a negative feedback mechanism.
  2. Describe the role of the receptor, control center and effector in a negative feedback loop.
  3. How do negative and positive feedback mechanisms differ?
  4. What are examples of negative feedback mechanisms besides body temperature and blood glucose regulation?