A reflex action is an automatic response that occurs spontaneously and without conscious control. It acts as a protection against injuries and dangerous situations.
For example, a little child may not know how the needle-shaped spike on the cactus may hurt, however the child's body will know.
This reflex action involves three types of neurones:
- Afferent neurone.
- Efferent neurone.
When a child's hand touches the cactus's needle shaped spike, the sensory receptors in the child's finger are triggered to send a nerve impulse through the afferent neurone.
The nerve impulse travels along the afferent neurone and passes through the synapse to an interneurone (which is located in the grey matter of the spinal cord). The nerve impulse the passes another synapse to the efferent neurone.
The nerve impulse travels along the efferent neurone to the muscles (or the effectors) in the child's hand. The muscles contract and the child moves his/her hand away from the cactus's spike.