GCSE Biology · AQA 8461 · Topic 4.5
Homeostasis and response
Key points
- Homeostasis keeps internal conditions (blood glucose, body temperature, water levels) stable for enzymes and cells to work.
- Control systems have receptors, a coordination centre (brain, spinal cord or pancreas) and effectors (muscles or glands).
- The nervous system gives fast, short-lived responses using electrical impulses; reflexes are automatic.
- The endocrine system uses hormones carried in the blood; responses are slower but last longer.
- Hormones control blood glucose, the menstrual cycle, metabolism and water balance.
- Plants respond to light and gravity using hormones such as auxin.
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Your body keeps its internal conditions remarkably steady even when the world outside changes. This topic explains how the nervous and hormonal systems detect changes and respond, and how plants coordinate their growth using hormones.
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