electrical synapse (gap junction)

An electrical synapse is a spot where two neighboring neurons are joined by tiny tunnels, letting their electrical signals pass straight from one cell into the next. Most neurons talk to each other across a narrow gap by squirting out chemical messengers, like passing a note hand-to-hand. An electrical synapse skips that step: it is more like two rooms connected by an open doorway, so the electrical charge simply flows through without being converted into a chemical and back again.

The doorways themselves are called gap junctions. Each one is built from matching ring-shaped proteins, one ring in each cell's outer skin, that line up to form a pore narrow enough to block big molecules but wide enough for the small charged particles (ions) that carry electrical current. Because the signal does not stop to release chemicals, electrical synapses are extremely fast and can run in both directions. They are common where many cells need to fire in near-perfect unison, such as in the heart or in groups of neurons that must respond as one.