# Explain how the body responds to a sustained drop in core body temperature, such as during prolonged exposure to a cold environment, to restore normal temperature.

> IB DP Biology Higher Level (2023 syllabus) — D3.3 Homeostasis · Explain · 4 marks

## Mark scheme (4 marks)

1. Thermoreceptors in the skin and/or hypothalamus detect a fall in core body temperature
2. The hypothalamus acts as a thermoregulatory centre / integration centre and sends nerve impulses to effectors
3. Shivering occurs — rapid involuntary skeletal muscle contractions generate heat through increased cellular respiration
4. Vasoconstriction of skin arterioles reduces blood flow to the skin surface, reducing heat loss by radiation/conduction/convection

## Related

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