GCSE Biology · AQA 8461 · Topic 4.5.1
Homeostasis
Key points
- Homeostasis is the regulation of a stable internal environment in response to internal and external changes.
- Conditions controlled include blood glucose concentration, body temperature and water levels.
- Automatic control systems may be nervous or chemical. All include receptors (detect stimuli), a coordination centre (processes the information) and effectors (bring about a response).
- Many work by negative feedback: if a level rises, changes bring it back down, and if it falls, changes bring it back up.
- Keeping conditions steady matters because enzymes work best at certain temperatures and pH, and cells can be damaged by water gain or loss.
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Homeostasis is the regulation of the internal conditions of a cell or organism to keep them suitable for life. Cells only work properly within narrow limits, so the body constantly detects and corrects changes.
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