Nerve Cells

A cell shaped like a tree

Nerve cells (scientists call them neurons, NOOR-ons) look like a little tree with roots, a trunk, and branches. Each part has a job:

• Dendrites are the branches. They listen for messages from other cells.
• The cell body has the nucleus, the cell's boss.
• The axon is a long tail that sends the message onward. Many axons wear a fatty coat, like the plastic around a wire, that makes messages go faster.

How a message travels

Nerve cells talk using tiny sparks of electricity. Here's what happens when you wiggle your toes:

• 1. Your brain decides: "Wiggle!"
• 2. A little electric signal zooms down the axon, like a spark racing along a fuse.
• 3. At the end, there's a tiny gap between cells called a synapse (SIN-aps). Electricity can't jump it, so the cell lets out special chemicals that float across, like passing a note.
• 4. The next cell gets the note and sends its own spark. Message passed, toes wiggled!

Three kinds of messengers

Your brain has about 86 billion nerve cells, and lots more run through your body. They work as a team:

• Sensing nerve cells tell your brain what's happening: what you see, hear, smell, taste, and touch.
• Thinking nerve cells in your brain and spinal cord connect everything and decide what to do.
• Moving nerve cells carry orders to your muscles: "Run!" "Smile!" "Catch the ball!"

Sometimes there's no time to ask the brain. If you touch something hot, your spinal cord (the big bundle of nerves inside your backbone) sends a "pull away!" message right back to your hand. This is called a reflex. Your hand moves before your brain even feels the "ouch."

Taking care of your nerve cells

Most of your other cells get replaced, but most of the nerve cells in your brain stay with you your whole life. So they're worth taking care of!

• Sleep. While you sleep, your brain sorts out what you learned that day and stores memories.
• Wear a helmet. Your skull protects your brain, and a helmet helps when you bike, skate, or scooter.
• Keep learning. Every time you practice something, your nerve cells build stronger connections. That's how practice makes things easier!
• Move and eat well. Exercise and healthy food help send oxygen and fuel to your brain.

Nerve cell quiz