Homeostasis and temperature control — Edexcel GCSE Combined Science
What homeostasis is, and why the body keeps conditions such as blood glucose and body temperature within narrow limits.
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Homeostasis is maintaining a constant internal environment in response to internal and external change. The body keeps blood glucose concentration, body temperature and the water content of the blood within narrow limits. This matters because enzymes and cells work best in a narrow range of conditions. Many of these controls use negative feedback.
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Quick check questions
Define homeostasis.
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Maintaining a constant internal environment in response to internal and external change.
Why does a high body temperature stop reactions in cells? (Triple only)
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Enzymes are denatured, so substrates no longer fit the active site.
What happens to animal cells if the blood is too dilute? (Triple only)
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Water enters by osmosis. The cells swell and may burst.
Which part of the brain coordinates temperature control? (Triple only)
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The hypothalamus.
How does shivering warm the body? (Triple only)
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Muscles contract rapidly. Respiration in the muscle cells transfers energy as heat.
Frequently asked questions
Why is homeostasis important?
Homeostasis is important because enzymes and cells work best in a narrow range of conditions. If blood glucose concentration, body temperature or the water content of the blood drift too far, reactions in cells slow down or stop. The body responds to changes and brings each condition back to a set level, often using negative feedback.
Written and checked against the Edexcel GCSE Combined Science (1SC0) specification · Updated October 2026