# Do nerve cells contract when they fire? **URL:** \ **Category:** Factual Questions\ **Created:** [August 2, 2002, 4:52pm UTC](https://boards.straightdope.com/t/do-nerve-cells-contract-when-they-fire/122037 "2002-08-02T16:52:46Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [August 2, 2002, 4:52pm UTC](https://boards.straightdope.com/t/do-nerve-cells-contract-when-they-fire/122037/1 "2002-08-02T16:52:46Z")
I just read something in a book, written in the 1940s by a doctor of, shall we say, questionable repute: > [@](#): > > We place a small, sufficiently transparent worm (e.g. a meal worm) under a good microscope, so arranged that both the ganglion and its _fibers_ are in focus. […] This experiment will provide convincing evidence that _the autonomic nervous system is not rigid but actually contracts and expands._ The movements of the nerves are serpentine, slowly undulating, and occasionally jerky. They consistently precede the corresponding movements of the total organism by a fraction of a second: first the nerve and its rami contract, followed by the contraction of the musculature. Expansion proceeds in the same fashion. Now, I learned in my high school biology class that nerve cells send signals to the muscles they’re connected to, which cause the _muscle_ cells to contract. But the way this author describes it, it sounds like the _nerve cells_ – or at least the glial cells that accompany the nerve cells – _are themselves contracting and expanding._ Do nerves actually move when they fire impulses? Or was this doctor merely seeing the movements of the muscles in the the immediate vicinity of the nerves, which were pulling the nerves along with them? ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [August 2, 2002, 5:04pm UTC](https://boards.straightdope.com/t/do-nerve-cells-contract-when-they-fire/122037/2 "2002-08-02T17:04:17Z")
The technical name for a neuron firing is an “action potential”. In short, the doctor is full of it. Neurons communicate with each other by releasing neurotransmitter across a synapse when an action potential is generated. The size of the synapse is very important in how effective this communication is. If neurons were moving around at all, it would wreak havoc with the delicate balance of the system. Not true at all. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [August 2, 2002, 5:11pm UTC](https://boards.straightdope.com/t/do-nerve-cells-contract-when-they-fire/122037/3 "2002-08-02T17:11:20Z")
The technical name for a neuron firing is an “action potential”. In short, the doctor is full of it. Neurons communicate with each other by releasing neurotransmitter across a synapse when an action potential is generated. The size of the synapse is very important in how effective this communication is. If neurons were moving around at all, it would wreak havoc with the delicate balance of the system. Not true at all. ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [August 2, 2002, 11:35pm UTC](https://boards.straightdope.com/t/do-nerve-cells-contract-when-they-fire/122037/4 "2002-08-02T23:35:01Z")
Okay, neurons don’t budge when they release neurotransmitters in their end-buttons, or when they receive neurotransmitters at the “starting points” (whatever they’re called) of their dendrites. But do neurons move when an electrical impulse conducts down their length? (Not necessarily in such a way that the synaptic gap changes; the neurons might be waving sideways and carrying their neighbors with them. After all, the nerves in my arm have to move when I bend my elbow or my wrist, just to keep up with the rest of my arm (even though it’s my muscles that are actually contracting and causing my arm to move), so obviously it’s possible for neurons to move around without wreaking havok with their synaptic-system balance.) And if not, do the rest of the cells making up the nerve (the glial cells) move in response to this impulse travelling down the neuron or in response to the release of neurotransmitters?