Sensory neurone detects a stimuli via sensory receptors e.g. a hot pan
This sends an impulse up the sensory neuron to the brain or spinal column (together known as the central nervous system or CNS)
Here te impulse crosses over a synapse to a relay neurone via release of chemicals
This relay neuron carries it to a motor neuron, where it crosses another synapse
The impulse then runs down the motor neuron to a muscle (effector) which activates it causing movement e.g. dropping the hot pan
Note - the effector may also be a gland, causing hormone release, Also draw a synapse