Nervous System

Nervous System Facts

Nervous System ['nûr-vŭs] ['sĭs-təm]

A complex network of cells that relays messages from all parts of our body to and from our brain.

Our Nervous System

Nervous System diagram

Our nervous system is the message center of our body. Just the way that messages travel from one telephone to another, messages of the nervous system travel throughout the body to help the body function and stay safe. The nervous system is an amazing and complex network of cells that relay messages from all parts of our body to our brain.

The spinal cord is the main highway on which these messages travel. Messages can travel in a short span of time so that it is almost instantaneous. Let's take a look at the parts of the nervous system and their jobs.

The Brain

X ray with brain and spinal cord

The brain is housed in the skull and is a most complex organ. Scientists continue to learn new things about the brain and how it works. The brain weighs about three pounds and is folded and grooved to store lots and lots of information. The brain regulates everything from our breathing and our heartbeats to what our favorite flavor of ice cream is. It helps us gain information about our environment through the use of our senses and it triggers reflex responses to keep us safe. The brain tells our legs to move when we walk or our throat to swallow when we eat. The brain houses memories too.

The Spinal Cord

Doctor showing anatomical spine in clinic

The spinal cord is about 18 inches long in an adult and is protected by special bones called the vertebrae. It is also sometimes called the spine. These bones are linked in a special way that allows us to bend and turn. Inside the vertebrae is a cord of nerves attached to the brain that branch out and carry messages from all parts of our body to and from the brain.

When we touch something with our finger, for example, a message is sent to the brain to say "this is soft," or "this is hot," or "this is a pencil." At nearly the exact same time, the brain will tell the finger to jump back if touching that object causes pain.

The Nerves

Neurons and nervous system

Throughout our body lies a huge network of nerves or neurons. These neurons are in some cases so small that they can only be seen under a microscope. They are threadlike cells that run from the spinal cord out to every area of our body. They allow us to experience our world, to touch, taste, see, hear, smell, and move. They tell us when it is too hot or that the wind is blowing. They also tell us to cover our eyes when the sun is too bright or that the bug crawling on our arm tickles. The nerves provide us with information, but they also tell our body to respond to pain, temperature, or other sensations too.


The nervous system governs all the working parts of our body — even some that we are unaware of. For example, you do not need to tell your heart to beat. We don't need to remind ourselves to breathe. These functions of the body are called involuntary reflexes. Our body does these things without our conscious effort. Sneezing, coughing, and blinking are also forms of involuntary reflexes.

panoramic shot of pediatrist examining kid with reflex hammer

We also have voluntary reflexes. Voluntary reflexes tend to be learned behaviors that we do without really thinking. Kicking a soccer ball as it rolls toward your foot is something that you had to learn how to do. But the thought process involved in kicking it becomes easier and less concious over time. The message from the brain to the nerves is often slower than an involuntary reflex because it must make two trips — one from the brain to tell the body something and then the response to actually do that thing — but it is still so fast that one wouldn't know the difference. Habits like biting your nails or popping your knuckles would be considered voluntary reflexes.

Top 10 Questions

December 2012

Thanks to Dr. Mary River, Neurologist, St. Alphonsus Hospital, Boise for the answers.

  1. Why are nerves so important to our body?

    Nerves are important to sense what's going on around you or within you. They tell your body where you are or what's around you. They tell your heart to speed up or slow down, your stomach when it's full, and they let your bladder know when you need to go to the bathroom. They are very important for every part of our functioning. (From Madeline at Anser Charter School in Boise)

  2. What are nerves made out of?

    Nerves are made out of axons like the wire that's in an electrical cord. There is an axon, or wire, that transmits the energy. The axon is covered with a coating called a myelin sheath, which protects it, and also keeps the electricity that is traveling along the axon from leaking out. (From Sophie at Anser Charter School in Boise)

  3. When you get older, will you get more nerves?

    You generally don't grow more nerves. You can heal an injured nerve if the injury is not too deep. If you injure the myelin sheath, or coating, of a nerve, you can regrow the coating. That's what happens when you bruise your funny bone. If you actually injure the axon of a nerve, most of the time, it doesn't re-grow. (From Olivia at Anser Charter School in Boise)

  4. What does the nervous system look like?

    If you look at the nervous system without any covering or with the naked eye, it would look whitish and a lot like firm jello. If you look at it microscopically, you would see bundles of nerves going up and bundles of nerves going down. It would look a lot like electrical cords bundled together. (From Henri at Cynthia Mann Elementary School in Boise)

  5. How fast does it take for your brain to recognize that it got hurt?

    The nerve fibers that sense discomfort or pain transmit messages very, very quickly in order to keep you from being hurt. If you touch a hot pan, those nerves transmit the message very quickly in order to get you to pull your hand away from the hot pan as soon as possible and avoid further injury. It would be in the range of 200 miles per hour. (From Harrison at Anser Charter School in Boise)

  6. Why do nerves respond so fast?

    Nerves respond quickly in order to keep you out of danger. If you step on a tack, then the nerve that you stimulated by doing that has to travel very quickly up to your brain to keep you from stepping on it further. Then a message travels back down allowing you to quickly step off the tack. This fast response helps keep you out of danger. (From Reid at Cynthia Mann Elementary School in Boise)

  7. Why does a nerve not regenerate when it gets harmed?

    Some nerves do regenerate. In the peripheral nervous system, the arms and legs, if a nerve is injured, it can sometimes re-grow if it hasn't been injured too severely. Most of the time, they don't. The number we are born with is the number that we get. You have to take good care of your nerves. (From Grant at Anser Charter School in Boise)

  8. Does the nervous system create fear?

    The nervous system doesn't create fear. It responds to fear. If you are walking in the woods and a bear shows up, your eyes see the bear. A message is then sent to the rest of the brain and the brain reacts, or responds, to that stimulation. (From Cooper at Anser Charter School in Boise)

  9. What makes people ticklish?

    There isn't a specific answer to that. The thought is that ticklish areas, like the bottom of your feet or under your arms, tend to be vulnerable. When they feel that something is going to happen, they withdraw for protection. (From Maddie at Trail Wind Elementary School in Boise)

  10. Why does it hurt so much when you hurt your elbow?

    It's not funny even though it is called the funny bone. The ulnar nerve is a nerve that goes to the pinky finger and half of the ring finger. It travels through a bony canal in the elbow. That groove of the canal in the elbow does not have a lot of protection. If you bang it, you actually bruise or shock the nerve. (From Wesley at Anser Charter School in Boise)