I believe the answer to your question is the synapse. "In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell." Typically a synapse is the space between the axon and the dendrite. It is within the space that a neurotransmitter is released. The neurotransmitter carries messages from one neuron to another.
There are two different kinds of synapses:
- Chemical Synapse-a neurotransmitter is released to carry messages between neurons.
- Electrical Synapse-are channels that are capable of passing electrical current. " Electrical synapses are often found in neural systems that require the fastest possible response, such as defensive reflexes."