synapse

A synapse is the tiny meeting point where one nerve cell passes a message to another cell — usually another nerve cell, but sometimes a muscle or a gland. Think of it like two people standing close together but not quite touching: one whispers, the other listens. The cell sending the message and the cell receiving it do not actually fuse; there is a microscopic gap between them, and the whole job of the synapse is to carry the signal across that gap.

Most synapses pass their message using chemicals rather than direct electrical contact. When an electrical pulse arrives at the end of the sending cell, it triggers the release of small chemical messengers called neurotransmitters into the gap. These drift across, land on matching receptors on the receiving cell like keys fitting into locks, and nudge that cell either to fire its own signal or to stay quiet. Because each synapse can be strengthened, weakened, or rewired with use, synapses are where learning, memory, and nearly all communication in the brain physically take shape.