The reflex arc is essential in producing a quick involuntary response aimed to prevent injury in an individual. In response to a stimulus (such as intense heat/fire), the sensory neuron detects this and transmits an electrical impulse to the relay neuron via a synapse with the release of neurotransmitters into the synapse. The electrical impulse is then relayed to the motor neuron via another synapse between the relay neuron and the motor neuron. The motor neuron communicates with the muscle associated with the external stimuli and via synapse and the diffusion of neurotransmitters, to produce muscle contract away from the harmful stimulus.