Beautiful synapse: When a nerve impulse reaches the synapse at the end of a neuron, it cannot pass directly to the next one. Instead, it triggers the neuron to release a chemical neurotransmitter. The neurotransmitter drifts across the gap between the two neurons. On reaching the other side, it fits into a tailor-made receptor on the surface of the target neuron, like a key in a lock. This docking process converts the chemical signal back into an electrical nerve impulse.