Reflex Action:Reflex actions involve three types of neurons:Sensory neuronsMotor neuronsRelay neurons - these connect a sensory neuron and motor neuron. They're located in the central nervous system (CNS)AUTOMATIC RESPONSES ARE CALLED REFLEXES.
Synapses:The electrical impulse travels along the axon which triggers the nerve-ending of a neuron to secrete neurotransmitters (chemical messengers). These chemicals diffuse across the synapse (the gap) and bind with the receptor molecules on the members of the next neuron. The second neuron's receptor molecules only bind to specific chemicals released from the first neuron. This then stimulates the second neuron to transmit the electrical impulse.