- The Nervous System
- A stimulus is a change in environment e.g. light, sound, touch or pressure.
- Receptors are groups of cell which are sensitive to a stimulus.
- You have five different sense organs which contain different receptors: eyes, ears, nose, tongue, skin.
- 1. When a stimulus is detected by receptors in a sense organ electrical impulses are sent along sensory neurone to the CNS.
- 2. The CNS then sends the electrical impulse to an effector along a motor neurone. The effector then responds to the stimulus.
- Sensory neurones carry nerve impulses from the receptors in the sense organs to the CNS.
- Relay neurones carry nerve impulses from sensory neurones to motor neurones.
- Motor neurones carry nerve impulses from the CNS to the effectors.