Structure and function of the nervous systemSpec 4.5.2.1
In short
The nervous system enables humans to react to their surroundings and to coordinate their behaviour. Receptors detect a stimulus, and neurones carry information as electrical impulses to the central nervous system (CNS), which is the brain and spinal cord. The CNS coordinates the response of effectors: muscles contracting or glands secreting hormones.
The nervous system enables humans to react to their surroundings and to coordinate their behaviour.
Information from receptors passes along cells called neurones as electrical impulses to the central nervous system (CNS). The CNS is the brain and spinal cord. The CNS coordinates the response of effectors, which may be muscles contracting or glands secreting hormones.
- Stimulus (a change in the environment)
- Receptor detects the stimulus
- Coordinator (the CNS) processes the information
- Effector (a muscle or a gland)
- Response
How the structure suits the function
| Part | Adaptation | Why it helps |
|---|---|---|
| Receptors | Each type is sensitive to one kind of stimulus | The body only picks up the changes it needs to respond to |
| Neurones | Long cells that carry electrical impulses | Impulses travel quickly over long distances between receptors, the CNS and effectors |
| CNS | The brain and spinal cord receive information and send out a coordinated response | The right effectors respond together |
| Effectors | Muscles contract; glands secrete hormones | They carry out the response |
Say that the CNS is the brain and spinal cord. The neurones carry the impulses, but they are not the coordinator.
Written and checked against the AQA GCSE Biology (8461) specification · Updated October 2026