Dr. Universe: Why are brains mushy? – First Graders, Waller Road Elementary, Puyallup, Wash.
Dear First Graders,
You’re right, brains are quite mushy. It turns out the three-pound organ between your ears is mostly made up of water and fat.
I found out all about brains from my friend Jim Peters, a neuroscientist at Washington State University.
“It’s gooey. It really is squishy,” he said. “When it is warm, it is kind of like butter.”
The brain may be soft but it is surrounded by a tough layer called the dura materto help protect it. I also found out the brain actually floats around in a kind of liquid. This liquid helps keep the brain from touching the bone of your skull.
The bones in your body are actually made up mostly of minerals, like calcium, which give them strength and hardness. If you bonk your head on something, the bone in your skull is a great material to help protect your squishy brain.
Still, bone can sometimes crack or break. That’s why it is so important to wear a helmet when you are being an adventurous rock climber, bicyclist, or playing football. It protects both your tough skull and squishy brain.
Part of the reason it is so important for brains to be soft is because they need some flexibility to work. The brain can change itself—the actual connections and the way it functions—and helps us make different thoughts and memories throughout our lives.
The brain is actually made of lots of tiny parts called neurons. When you were born, you had many more of these neurons than you do today. As you grow and learn your brain trims these neurons to make just the right connections and circuits.
These neurons that make up the brain communicate with each other to help your body do lots of different things—move, smell, see, touch, and sense the world around you. There are billions and billions of them.
Peters told me these cells are surrounded in a coat of fat called the membrane. The membrane is like a wall that surrounds the cell and gives it a good structure. That way all the parts inside the cell can stay together.
When cells communicate, they use electricity to make it happen. That’s right— your brain is full of electricity. The fatty membrane helps direct the flow of electricity to the right spot so that it can release chemicals called neurotransmitters. So in a way, the squishiness helps brain cells make connections and pass those messages to other brain cells.
The brain is not only soft, but it has kind of bumpy, grooved, or wrinkly surface. If you were to unfold the brain, it would take up quite a bit of space. Some people have estimated it would cover an area the size of one to two pages of a newspaper. That’s a lot of brain tucked into your skull.
Our mushy brains do all kinds of things for us, including helping you read this very sentence and ask big questions about our world.