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 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 heart beats 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
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.
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.
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.