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Ask Dr. Universe human body
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Why is snot green? – William, 7, United Kingdom

Dear William,

There are lots of unpleasant things about being sick. Leaking slimy green snot is near the top of my yuck list.

I talked about it with my friend Linda Eddy. She’s a nurse for kids. She runs the nursing program on the Vancouver campus of Washington State University.

She told me that snot is normally clear. It turns yellow or green when our bodies fight germs that can make us sick.

Snot is also called mucus. It’s a thin, slippery liquid that covers many of the surfaces inside our bodies. You can find mucus in your nose, mouth and eyes. It … » More …

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Why do we need to hydrate? – Victor, 9, Ohio

Dear Victor,

Is there anything better than lapping up cool water on a hot day?

I talked about why we need to hydrate with my friend Ed Johnson. He teaches classes about the human body in the School of Biological Sciences at Washington State University.

It turns out that up to 60% of an adult human’s body is water. A kid’s body contains even more water than a grown up. When you were a baby, you were about 78% water.

Humans use that water for all kinds of things. It keeps you cool when you sweat. It removes waste when you pee. It moves important stuff around inside your body. It even cushions your brain and spinal cord.

But staying hydrated is really about your cells.

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Why do we have nose hairs? – James and Zion, 10, Virginia

Dear James and Zion,

Despite being a curious science cat, I must confess I haven’t spent much time looking up human noses. But I have noticed that human nostrils can be a bit…furry.

I talked about what’s inside your nose with my friend Edward Johnson. He teaches classes about the human body in the School of Biological Sciences at Washington State University.

He told me that nose hairs only grow in your nose’s vestibule. That’s the inside of the part of your nostrils that you can flare out. The nose hair’s job is to filter the air you breathe in through your nose.

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