# A student is investigating how the body maintains a stable internal environment. Explain how the nervous system and the hormonal system work together to maintain homeostasis, including what is meant by a negative feedback mechanism.

> OCR A-Level Biology B — Advancing Biology (H422) — 5.5 Communication and homeostasis · Explain · 5 marks

> The human body constantly monitors and adjusts its internal conditions, such as blood glucose concentration and core body temperature, to keep them within narrow limits. This process is called homeostasis.

## Mark scheme (5 marks)

1. Homeostasis is the maintenance of a stable internal environment / keeping internal conditions within narrow limits
2. Receptors detect a change / stimulus in internal conditions
3. A coordination centre (e.g. the brain or pancreas) processes the information and sends a signal via the nervous system (nerve impulses) or hormonal system (hormones in the blood) to effectors
4. Effectors (muscles or glands) bring about a response to counteract / reverse the change
5. Negative feedback is the process by which the response reverses / reduces the original change, returning conditions back to the set point / normal level

## Key terms

- [homeostasis](https://www.gradenine.co.uk/glossary/homeostasis)
- [negative feedback](https://www.gradenine.co.uk/glossary/negative-feedback)

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-investigating-how-the-27d9c2c1) · Published by Druglandscape Ltd.