Shivering with fear, you race to your car after walking out of the horror film. The zombies aren't tasting any part of your brain! Fictional or not, zombies have a good reason for wanting to eat our brains. They want to eat the most important organ in your body. The brain controls the entire human body. But it doesn't work alone.
The shivering that you couldn't shut down? The sweating that left embarrassing stains on your shirt? The goosebumps that transformed your hairs into dark stalagmites? These are controlled by the nervous system.
The brain itself is made up of different parts. The cerebrum is the big, wrinkly part that we often picture when we think of a brain. It helps us with voluntary actions, like when you are brainstorming writing topics or hitting a tennis ball. The cerebellum is in the back of the brain, and helps us with movement and balance. The brainstem is the nervous system's secretary. It connects the brain to the spinal cord. It helps us with involuntary actions, like breathing and digesting.
The brain needs nerves to help send information to the rest of the body. The most important nerves are in the spinal cord. The spinal cord is a bundle of nerves inside your spinal column. But just what are nerves made of?
Nerves are so small that you can't see them without a microscope. There are more nerve cells in the human brain than there are stars in the whole Milky Way. The nervous system is made of millions of tiny brain cells called neurons. Sensory neurons help us experience the world around us. Stimuli such as light, taste, or touch are picked up by sensory neurons. These neurons communicate with the nervous system to help the body react.
When you were born, you already had all the neurons you will ever have. They were not connected to each other. As you learn new things, your neurons pass messages to each other over and over, until the brain makes a connection between them. This pathway is a bridge that creates a shortcut between neurons. As you build more pathways, you can do more things and do them better and better.
Think about the first time you ever wrote a sentence. You had to think about shaping the letters, holding the pencil, making the lines, and spelling the words, all at once. But as you practiced more, the neurons got used to sending the same messages back and forth. Eventually, a pathway was built in your brain. Now, you can write sentences without even thinking about it. Your neurons are able to use their 'sentence writing' pathway.
It takes a lot of neurons to do all that work. If we lined up all the neurons in our body, we'd be able to make a string 1,000km long. Scientists believe that the brain has the capacity to store up to 1,000 terabytes of information. That's the equivalent of about fifteen full libraries.
But be careful: as we get older, the brain loses almost one gram of its weight per year! Some sicknesses, like Alzheimer's disease, can cause our brain to degenerate. We become more forgetful. Some diseases are progressive, causing us to experience worse symptoms over time. Some diseases are inherited, meaning they might be more difficult to prevent. So if you have a great idea, start acting now before your brain can't or won't do the work anymore!