Synapse. Computer artwork of a synapse, the junction between two nerve cells. Synapses transmit electrical signals from one nerve cell to the next. When the signal reaches the synapse it triggers the release of chemicals called neurotransmitters (blue spheres) from vesicles in the terminal swelling of the presynaptic cell. The neurotransmitters cross a microscopic gap called the synaptic cleft and bind to the receptor nerve cell, causing it to propagate an electrical impulse.