Feedback
Introduced| English | Meaning |
|---|---|
| feedback/ˈfiːdbæk/ | Information about an outcome returned to a person or system to guide subsequent action. |
| homeostasis/ˌhəʊmiːəˈstɑːsiz/ | Maintaining a relatively stable internal environment despite external or internal changes. |
| set point/set pɔɪnt/ | A reference level that a regulatory system acts to maintain. |
| negative feedback/ˈneɡətɪv ˈfiːdbæk/ | A control process in which a change triggers responses that oppose that change. |
| positive feedback/ˈpɒzɪtɪv ˈfiːdbæk/ | positive feedback |
Keeping things steady
- Your body temperature barely moves, even on a hot or cold day.
- Your blood sugar stays roughly level, whether you just ate or not.
- Cells and bodies work hard to hold their conditions steady.
- The trick that makes this possible is feedback.
Homeostasis and the set point
- Homeostasis 稳态 is keeping internal conditions steady.
- The body has a target value called the set point 设定点.
- Sensors compare the real value with the set point.
- Any difference triggers a correction.
Homeostasis is…
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Homeostasis keeps internal conditions (temperature, glucose, water) steady around a set point.
Negative feedback corrects
- Feedback 反馈 means a change loops back to influence the system.
- Negative feedback 负反馈 reverses a change, pushing it back to the set point.
- Too hot? The body cools down. Too cold? It warms up.
- This constant correction is what keeps you stable.
Negative feedback
correction back to a set point
Drag the disturbance. A change is corrected back to the set point — the basis of homeostasis.
In negative feedback, a change is…
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Negative feedback reverses a change, pushing the value back toward its set point — the basis of homeostasis.
The target value that the body tries to hold is called the ____ point.
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The body compares the current value with the set point and corrects any difference.
Positive feedback amplifies
- Positive feedback 正反馈 does the opposite — it makes a change bigger.
- One change triggers more of the same, building up fast.
- It is rarer, used for events that need to finish quickly.
- Childbirth and blood clotting both use positive feedback.
Positive feedback corrects a change and returns the body to its set point.
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False. That is negative feedback. Positive feedback amplifies a change, as in childbirth contractions.
Select all true statements about feedback.
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Negative feedback reduces a change, it does not amplify it. The other three are correct.
Most control in the body is negative feedback — it reduces a change. Do not mix it up with positive feedback, which amplifies. "Negative" does not mean bad; it means the response opposes the change and brings things back to normal.
A thermostat for your body:
- If you get too warm, sensors detect it (value above set point).
- Negative feedback kicks in: you sweat and blood vessels widen to lose heat.
- Your temperature falls back to the set point — then the correction switches off.
Homeostasis keeps the body's conditions steady near a set point. Negative feedback corrects a change by reversing it, restoring the set point — this runs most of the body's control. Positive feedback instead amplifies a change and is used only for special, fast events.
Write from negative feedback
- Blood glucose rises after a meal.
- Insulin causes cells to take glucose in, and the level comes back down.
What kind of feedback is this?
Negative feedback brings a variable back toward its set point.
What feedback lowers glucose after the rise?
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The response opposes the original change.