Ask Dr. Universe: Why are brains mushy?

Dr. Universe: Why are brains mushy? – First-graders at Waller Road Elementary, Puyallup

Dear first-graders,

You’re right, brains are quite mushy. It turns out the 3-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 might be soft, but it is surrounded by a tough layer called the dura mater to help protect it. I also found out the brain 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 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 your tough skull and squishy brain.

Part of the reason it is important for brains to be soft is because they need flexibility to work. The brain can change itself – the connections and way it functions – and helps us make thoughts and memories throughout our lives.

The brain is made of lots of tiny parts called neurons. When you were born, you had many more of these neurons than 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 also has kind of a 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.

Sincerely,

Dr. Universe

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