The body electric

We all know that brains and muscles operate electrically. But almost no one seems aware that our body’s electricity has very quirky, variable characteristics. (Photo by Dion Ogust)

We take electricity for granted. But it wasn’t always this way. It would have been fun to be alive in the latter half of the 19th century, when it was the cat’s meow. New discoveries were announced weekly. Museums drew crowds around glass bottles (“Crookes Tubes”) containing thin gases that colorfully glowed when high voltages passed through them. Your visit to your doctor usually included a conversation about electrical baths, or having electrical probes placed in various body orifices so that your depleted energy could be revivified by this essential and still-mysterious force believed to permeate the universe.

We’re still not fully over our love affair, and I’m still enthralled by my solar panels and hybrid electric car. But what about the intimate electricity in our bodies? We all know that brains and muscles operate electrically. We know that the right ratio of sodium and potassium electrolytes is necessary to maintain our body’s battery. But almost no one seems aware that our body’s electricity has very quirky, variable characteristics.


For one thing, it’s surprisingly slow. When we consider lightning in the sky or the current running in copper wires, we’re talking about things zooming at 96 percent of light’s velocity.  House current travels at 175,000 miles per second. But the electricity running through our nerves and brains doesn’t even go one percent as fast as this. What’s weird is how much it varies.

The most common electrical speed in our bodies is 250 miles per hour – not 250 miles per second, but per hour. This highest-of-all-body-speeds is used for important tasks such as reflex actions. Say you’re on a camping trip and you step outside the tent in the middle of the night. Your bare foot steps down on something cold and slimy, and you instantly yank it away because maybe it’s a snake. This perception of danger and the yanking reflex all operated at 250 miles per hour. Sure, that’s slow compared to electricity in our home wiring; but it’s still more than three times faster than we drive down the Thruway.

My favorite demonstration of how fast these electrical signals operate can be easily performed: Right now, flail your arms rapidly around your body, paying attention to the location of your hands. Doing this, you’ll find that you always know exactly where your hands are positioned at every instant, no matter how fast you’re moving them. This proves that the signals carrying this information must be extremely fast. This was obviously a necessary use of such high speed, because otherwise you might smash your hand into something and injure it.

What about thinking? How fast do we think? You will be nonplussed to hear that the electrical impulses involved in thinking only move at 70 miles per hour. It’s as if nature decided, “There goes Alyssa, trying to decide whether she wants butter or cream cheese on her bagel. Well, there’s no rush.” (I used the word nonplussed deliberately, because these days it’s tautological. You can never go wrong using it, because nonplussed can mean greatly surprised or not surprised at all.)

Are we done with this, or do our bodies contain still-slower electrical speeds? You’ll be nonplussed when you hear that some electrical signals only travel at three miles per hour, which is the same as two feet per second. Oddly enough, these are pain signals. Again, it’s as if Mother Nature, wearing her architect’s hat (or maybe her sadist’s hat), said, “Bob just slammed his toe into a door yet again? That’s the second time this month. Well, there’s certainly no hurry in delivering the bad news.”

You’re skeptical? Well, think about when you last smashed your toe into something. Remember that excruciating two- or three-second delay, those moments of limbo before you suddenly felt the stabbing pain? That’s because, traveling at just two feet per second, the pain signal required between two and three seconds to travel the five or six feet from your toe to your brain.

Was this a bad design or a good one? Should we envy the lightning-fast speed of the electricity of lightning? Or does this whole issue leave us nonplussed?

Want to know more? To read Bob’s previous columns, visit our Almanac Weekly website at Check out Bob’s new podcast, Astounding Universe, co-hosted by Pulse of the Planet’s Jim Metzner.

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