A Nervous Journey Illustration showing an impulse traveling through a neuron.
Written by: Brett Szymik
Illustrated by: Sabine Deviche and James Baxter

show/hide words to know

Action potential: a small electrical event which is how information is passed from neuron to neuron.

Cell: a tiny building block that contains all the information necessary for the survival of any plant or animal. It is also the smallest unit of life... more

Neuron: a special cell which is part of the nervous system. Neurons work together with other cells to pass chemical and electrical signals throughout the body... more

Trillion: 1,000,000,000,000.

Cartoon boy wiggling his big toe.


Let’s take a journey. It is going to be a fast one, so be prepared. Where are we going? We are going to start at your head and end up at your toes. It may not seem like a long trip, but it is going to be fast. It may be the shortest and fastest trip of your life. Are you ready? Let’s begin. Wiggle your big toe. Okay, we’re done. You might be saying, ‘That’s it?’  We said it was going to be a fast ride!

You just sent a message with an electrical signal from your brain to the muscles in your toe and bingo!  it moves. Just how fast was the signal moving? The electrical signals in your body can move as fast as 150 meters per second.

How fast is that? Well, in the amount of time it takes you to say "Mississippi" three times, a nerve could send an electrical signal the length of a football field and back. That is fast! Now that you know how fast a nerve impulse can travel, let’s take a look at the system that is the highway for these electrical signals. 



The human body is made of trillions of tiny cells. Each cell is so small you need a microscope to see them. Your skin, your hair, your eyes  all are made up of cells.  Different types of cells do different jobs. Muscle cells move your body.  Skin cells protect your body.  One special type of cell, neurons, allow your brain to send messages to every part of your body.

What Is the Nervous System?

nervous system

The nervous system includes the brain, spinal cord, and nerves. Click on the image to see a larger version.

The nervous system is the group of cells in the brain, spinal cord and nerves that are all made out of neurons. When we talk about the nervous system we are talking about the brain, spinal cord, and nerves. 

Each of these is made of a specific type of cell called a neuron, or you might have heard them called brain cells.

Passing Along the Message

The center of the nervous system is the brain.  The brain takes in what your eyes see and what your ears hear. If you decide that you want to move around, your brain tells your muscles to do it.  You can think of your nervous system as a relay team passing a baton from one runner to the next.  But instead of runners, you have cells, and instead of a baton, you have information.  A neuron in your brain starts the relay, handing its information to the next cell, which passes the information to another cell.  In the end, the information reaches its destination and causes a change  maybe a muscle contracts.  The "information" baton passed from neuron to neuron is usually a small electrical event called an action potential.

The nervous system as a big relay team, where the baton passed from runner to runner is the message from the brain.



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Additional Images from Wikimedia Commons.

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Bibliographic details:

  • Article: A Nervous Journey
  • Author(s): Brett Szymik
  • Publisher: Arizona State University School of Life Sciences Ask A Biologist
  • Site name: ASU - Ask A Biologist
  • Date published: May 3, 2011
  • Date accessed: July 15, 2024
  • Link: https://askabiologist.asu.edu/explore/nervous-journey

APA Style

Brett Szymik. (2011, May 03). A Nervous Journey. ASU - Ask A Biologist. Retrieved July 15, 2024 from https://askabiologist.asu.edu/explore/nervous-journey

American Psychological Association. For more info, see http://owl.english.purdue.edu/owl/resource/560/10/

Chicago Manual of Style

Brett Szymik. "A Nervous Journey". ASU - Ask A Biologist. 03 May, 2011. https://askabiologist.asu.edu/explore/nervous-journey

MLA 2017 Style

Brett Szymik. "A Nervous Journey". ASU - Ask A Biologist. 03 May 2011. ASU - Ask A Biologist, Web. 15 Jul 2024. https://askabiologist.asu.edu/explore/nervous-journey

Modern Language Association, 7th Ed. For more info, see http://owl.english.purdue.edu/owl/resource/747/08/
Neuron picture
Nerves are located throughout the human body. They control, sense and send signals between different parts of the body. Here is a nervous experiment that you can try on your own.

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