Free Introduction to the Nervous System revision notes for OCR A Level Biology – covering specification point 5.1.1 (a).
The nervous system is a fast and highly coordinated communication network that allows multicellular organisms to detect changes in their internal and external environments and produce rapid, short-term responses.
Neuronal communication consists of three main components:
- Sensory receptors detect changes (stimuli) and convert the energy of a stimulus into electrical signals (transduce).
- Neurones transmit electrical impulses to specific components of the body.
- Synapses transfer and coordinate electrical signals between neurones using chemicals (neurotransmitters).
The Nervous System as an Effective Communication System
The table below outlines the features of an effective communication system, and the features of the nervous system that make it effective:
| Feature | How the nervous system enables this |
|---|---|
| Coverage | The central and peripheral nervous systems link all areas of the body, and their receptors and effectors, through sensory, relay and motor neurones. |
| Speed | Action potentials transmit information quickly along neurones. |
| Specificity | Sensory receptors respond to specific stimuli, and complementary receptors in synapses ensure electrical impulses are directed to specific cells. |
| Coordination | Coordinating (e.g. brain, spinal cord) process sensory input and signal appropriate effectors. |
| Duration of Response | Effectors signalled by the nervous system typically produce immediate and short-lived responses (compared to the endocrine system). |
