# The human body constantly monitors and adjusts its internal conditions. Describe how the body detects and responds to a rise in core body temperature, and explain why maintaining a stable internal temperature is necessary for enzyme-controlled reactions.

> Pearson Edexcel A-Level Biology A (9BI0) — 4.6 Homeostasis · Describe and Explain · 5 marks

> Body temperature in a healthy adult is maintained at approximately 37 °C. When core temperature rises above this level, several automatic responses are triggered.

## Mark scheme (5 marks)

1. Receptors / thermoreceptors in the skin and/or hypothalamus detect the rise in temperature
2. Sweat glands produce more sweat / sweating increases
3. Vasodilation occurs — blood vessels near the skin surface widen / more blood flows to the skin, increasing heat loss
4. Enzymes have an optimum temperature; if temperature rises too far above 37 °C, the enzyme's shape / active site changes
5. If the active site changes shape, the substrate can no longer fit / enzyme–substrate complexes cannot form, so metabolic reactions slow or stop

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/the-human-body-constantly-monitors-and-0ab1522b) · Published by Druglandscape Ltd.