The human body must maintain a constant internal environment. Explain how the body detects and responds to a rise in core body temperature to restore normal temperature.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
During vigorous exercise, the core body temperature of a person rises above the normal set point of 37 °C.
Model answer (5 marks)
Thermoreceptors in the hypothalamus sense the rise in core temperature and send a signal to the hypothalamic temperature‑monitoring centre.
The hypothalamus activates the sympathetic nervous system, which stimulates sweat glands to produce more sweat.
Sweat evaporates from the skin, removing heat energy and cooling the body.
Simultaneously, the hypothalamus causes vasodilation of arterioles close to the skin, increasing blood flow to the surface.
These responses form a negative feedback loop that reduces the temperature change and restores the core temperature to the normal set point of 37 °C.
The hypothalamus activates the sympathetic nervous system, which stimulates sweat glands to produce more sweat.
Sweat evaporates from the skin, removing heat energy and cooling the body.
Simultaneously, the hypothalamus causes vasodilation of arterioles close to the skin, increasing blood flow to the surface.
These responses form a negative feedback loop that reduces the temperature change and restores the core temperature to the normal set point of 37 °C.
Examiner tips
- Use the word ‘thermoreceptors’ and ‘hypothalamus’ – these are key terms. Show the sequence: detection → hypothalamus → sweat glands & vasodilation → cooling. Mention negative feedback explicitly to hit the final mark.
Common mistakes
- Forgetting to name the hypothalamus as the temperature‑monitoring centre. Not linking vasodilation to increased skin blood flow. Using vague terms like ‘body reacts’ instead of specific mechanisms such as ‘sweat glands’ and ‘vasodilation’.
Mark scheme (5 marks)
- Thermoreceptors in the hypothalamus detect the rise in core body temperature / the hypothalamus acts as the temperature-monitoring centre
- Sweat glands are stimulated to produce more sweat / increased sweating occurs
- Sweat evaporates from the skin surface, transferring heat energy away from the body / cooling the body by evaporation
- Vasodilation occurs — blood vessels (arterioles) near the skin surface widen / more blood flows to the skin surface
- This is an example of negative feedback — the response reduces the change / returns body temperature back to the set point / normal temperature is restored
Related
- All Edexcel A-Level Biology A: Salters-Nuffield (9BN0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Homeostasis questions
- A person goes for a long run on a hot day. During the run, their body temperatur…
- A person has been sitting in a very cold room for an extended period of time. Th…
- A person has not eaten for several hours and their blood glucose concentration f…
- A student eats a large meal containing a lot of sugar. Explain how the body dete…