Negative Feedback
Biology: Cambridge International A Level, topic 14.1.2
Negative Feedback
Negative feedback is the mechanism that restores systems to the original level. The steps involved in these mechanisms are:
1) Detect change
- Change in the internal environment (stimulus) is detected by receptors.
- Receptors (e.g. thermoreceptors) are stimulated when the level is too high or too low (e.g. temperature).
2) Counteract change
- Receptors send a signal to the effectors through coordination systems (nervous system or endocrine system).
- The effectors counteract the change (e.g by restoring body temperature to 37°C).
- Negative feedback can only maintain the internal environment within a specific range. If a change is too dramatic, negative feedback may not be able to prevent it.
Multiple Negative Feedback Mechanisms
Multiple negative feedback mechanisms provide a greater degree of control of the internal environment.
More control
- Multiple feedback mechanisms provide more control because the body can respond to multiple changes away from the optimum.
- E.g. Body temperature can be reduced or increased by multiple mechanisms.
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Faster response
- Multiple feedback mechanisms also provide a faster response because the body can respond in more ways to a change away from the optimum.
- E.g. If body temperature decreases, negative feedback can increase body temperature by both shivering and vasoconstriction.
Test yourself on Negative Feedback
Which of the following statements about negative feedback are true?
What is the optimum human body temperature?
Stages Involved in Negative Feedback
What are the benefits of multiple feedback mechanisms?
Which of these are NOT a benefit of multiple negative feedback mechanisms?