Reflex Actions

Imagine you accidentally touch something very hot. You very quickly pull your hand away. The response is very fast, it needs to be.

This is what happens

Notice there are 3 types of neurone involved. Sensory, relay and motor.

The links between neurones are tiny gaps called synapses. The signal is passed from one neurone to another by the diffusion of chemicals.

Reflex actions need to be very fast. The brain is not needed.

Reflex actions are often inbuilt (e.g. knee jerk) or can be learnt (e.g. in martial arts)

REMEMBER

• Reflex actions are automatic and rapid. They often involve sensory, relay and motor neurones.
• Understand the role of receptors, sensory neurones, motor neurones, relay neurones, synapses and effectors in simple reflex actions.