How does the brain work in the body?

This is the first segment in our on-going series of Brain Day Questions, where we answer questions submitted by 7th grade students from Palo Alto and East Palo Alto classrooms. In our inaugural post, Dr. Adrienne Mueller explains how the brain works in the body. For more on the series, check out our Brain Day Questions kick-off post


How does the brain work in the body?

You can think of the brain like a central train station; with trains coming in from, and going out to, many different places. The train lines are nerves, and the trains are signals from different parts of the body. One signal might be a loud sound, another signal might be someone touching your hand. Some signals go directly into the brain, but a lot of them go to the spinal cord first, which is like an extension of the brain. The brain then collects all this different information, processes it in ways we still don’t fully and understand, and makes a plan of action. It then sends signals (outbound trains) out to your muscles to put that plan into effect.

 Your nervous system. Source: http://www.innerbody.com/anatomy-images/nervous_system.png

Your nervous system.
Source: http://www.innerbody.com/anatomy-images/nervous_system.png

 The Commuter Rail system in the Greater Boston area.  Source: https://en.wikipedia.org/wiki/MBTA_Commuter_Rail

The Commuter Rail system in the Greater Boston area. 
Source: https://en.wikipedia.org/wiki/MBTA_Commuter_Rail

Sometimes, a signal needs to be dealt with more quickly than it would take to travel all the way up to the brain and be processed. For example, if you touch something hot or sharp. That’s when your reflexes take over. The signals of heat and pain are sent to the spinal cord, which immediately sends another signal out to your muscles to pull your hand back. The signal also goes to your brain (that’s how you “feel” the heat), but the signal from your spinal cord has already pulled back your hand, to try to avoid further injury.