How digestion works: what happens to food after you eat it
Your digestive tract: why food in your stomach is still outside your body
A meal can sit in your stomach for hours and still not be inside your body. Your digestive tract is a tube with two open ends. So when does your food really get in?
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1
Saturday is moving day. Your friend Miva is moving into a new home on the third floor, and you and Rono carry her boxes up the stairs. By one o'clock, you are both very hungry.
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2
Lunch is on the floor, between the boxes. You eat a bowl of beans, rice and chicken. Rono has a big soda and a white bread roll.
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3
A few minutes later, your first bite is in your stomach. That sounds like the inside of your body. But it is not inside you yet.
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4
From your mouth to the other end, your gut (your digestive tract) is one long tube. Food travels along the inside of it. And this tube is open to the world at both ends.
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5
Think of a donut. A bean can pass through the hole and never be inside the dough. Your body is the dough, and your gut is the hole. Food in your gut is still outside you.
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6
Food gets into your body in one way only: it crosses the wall of your gut into your blood. This is called absorption. But the wall lets through only very small pieces. A bean, a grain of rice, a bit of chicken: all far too big.
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7
Chewing helps, but teeth only make small bits. Your body must cut your lunch much smaller, into pieces far too small to see. This cutting is digestion. Only after it can the pieces cross the wall, and only then are they inside you.
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8
This cutting does not start in your stomach. It already started in your mouth, before you swallowed. And it was not your teeth.
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Quick check
A cherry stone.
Show the answer
No. It stayed inside the tube of the gut the whole time and never crossed the wall. So it passed through without ever getting in.
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Go further
Two names for what you saw.