Feedback and Control

Feedback and Control


  • A process that maintains a stable internal environment in an organism.
  • Involves constant monitoring and adjustments as conditions change.
  • This is driven by feedback mechanisms that respond to changes in the system.

Negative Feedback

  • The most common type of feedback in biological systems.
  • Reduces the effect of changes and returns the system to its desired set point.
  • An example of this is body temperature regulation: When body temperature rises, mechanisms such as sweating and vasodilation (expanding blood vessels) are triggered to cool the body and bring it back to its normal temperature.

Positive Feedback

  • Less common than negative feedback, but still important.
  • Amplifies or increases the occurrence of events.
  • This feedback isn’t about restoring balance, but instead promotes a greater change in the same direction.
  • An example of this in the human body is the release of oxytocin to intensify labour contractions during childbirth.

Feedback Loops

  • Fundamental mechanisms used in control systems in biology.
  • Composed of a sensor (detects change), control centre (processes information) and an effector (brings about change).
  • The sensor records the current condition and sends this information to the control centre.
  • The control centre determines appropriate response and sends information to the effector.

Control of Blood Glucose Levels

  • A key example of homeostasis in human body, governed by feedback mechanisms.
  • When blood glucose levels rise (after eating), the pancreas releases insulin, promoting cells to absorb glucose, which then lowers blood glucose levels back to normal.
  • When blood glucose levels are low (e.g. during fasting), the pancreas releases glucagon which stimulates the release of stored glucose from the liver, raising blood glucose level.

Hormonal Control

  • Hormones are chemical messengers in the body.
  • They help in regulation and communication between different parts of the body.
  • Hormones like insulin and glucagon play crucial roles in maintaining homeostasis and regulating body’s metabolic activities.

Understanding these fundamental mechanisms of feedback and control is essential to grasp how our bodies maintain balance and respond to internal and external changes.