Scientists Say: Synapse

This is how brain cells ‘talk’ without touching

This artist’s drawing shows a synapse — the tiny space between two nerve cells, with chemical signals (small dots) shuttling back and forth.

cosmin4000/istockphoto

Synapse (noun, “SIN-apps”)

This is how brain cells can talk without ever touching. The synapse is a gap between two nerve cells. The cells pass messages across the space.

Synapses can be chemical or electrical. In a chemical synapse, one cell releases a small burst of chemicals — called neurotransmitters — into the space. This gap is between 20 and 40 nanometers wide (about 10 to 20 times the thickness of a strand of DNA).  The chemicals drift across the gap and bind to molecules on the other side, passing the message from cell to cell.

Electrical synapses are also called gap junctions, and they are much smaller — only 3.5 nanometers wide or so. That’s about twice as wide as a DNA strand. Molecules called channels link the two cells. Electrical signals pass through the channels, taking the message from one cell to the next.

The word “synapse” turns 120 years old in 2017. In 1897, the British scientist Charles Sherrington came up with the idea. But it was Arthur Verrall — a professor of classical literature — who gave the synapse its name that same year.

In a sentence

When neurotransmitters cross a synapse, scientists call the process neurotransmission.

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Bethany Brookshire is the staff writer at Science News for Students. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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