howthings.work · a picture encyclopedia for small children
The Human Body
Inside a person · by @virpo
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Inside every person is a busy machine: a brain that thinks, lungs that breathe, a heart that pumps and a tummy that turns food into energy. This person is see-through, so you can look inside.
Brain
Your brain sits safe inside your skull. It tells every part of your body what to do, even while you sleep.
- It sends messages along nerves, faster than a racing car.
- It remembers your favourite song and the way home.
- It never stops working, not even at night: it keeps you breathing and dreaming.
Lungs
When you breathe in, your two lungs puff up like balloons and take in the air you need.
- Air goes down the windpipe and into the lungs.
- The lungs pass the good part of the air, oxygen, into your blood.
- When you breathe out, you blow away the air your body has used.
Heart
Your heart is a muscle about the size of your fist. It squeezes again and again and pushes blood all around your body.
- Put your hand on your chest and you can feel it beat.
- When you run, it beats faster to send more blood to your legs.
- Blood goes out from the heart in red tubes and comes back in blue ones.
Stomach and liver
Food you swallow lands in your stomach, a stretchy bag that mashes it into a soup.
- The stomach squeezes and mixes the food with juices that break it down.
- The big red-brown liver next to it cleans the blood and helps with digestion.
- After a big meal your stomach stretches to hold it all.
Intestines
From the stomach, food goes into a very long tube, folded up so it fits in your tummy.
- On the way, the good parts of food go through the tube's walls into your blood.
- What your body can't use goes on to the end and leaves when you go to the toilet.
- The two bean-shaped kidneys clean water out of your blood and send it to your bladder.
Muscles
Muscles are the red, stretchy bundles under your skin. Every move you make, a muscle pulls.
- Muscles can only pull, never push. So they work in pairs: one bends your arm, another straightens it.
- The more you play and run, the stronger they get.
- Your heart is a muscle too, one that never gets tired.
Bones
Your bones are your skeleton, a frame inside you that holds you up and protects your soft insides.
- Where two bones meet there is a joint, like at your knee and elbow, so you can bend.
- Bones are alive and grow as you grow.
- Your skull protects your brain, and your ribs protect your heart and lungs.
Skin
Your skin covers you from head to toe. It keeps germs out, keeps water in and tells you when something is warm or cold.
- It's made of tiny pieces called cells, millions and millions of them.
- When you get hot, it sweats to cool you down.
- Look inside it: tap 'Inside: Skin' below.