How Your Body Digests Food

Take a bite of a roti or a piece of bread and chew it for a long, long time — much longer than you normally would. Something surprising happens: it starts to taste a little sweet. Nothing sweet was added. Your mouth did that.

Here is how. Your teeth cut and crush the food into small bits. Your tongue pushes the bits around and mixes them with salivaThe watery spit your mouth makes. It softens food and starts breaking it down.বাংলা: লালা · हिन्दी: लार — the watery spit your mouth makes all day. Saliva is not just water. It contains special helpers called enzymesTiny helpers in your body that break food into smaller pieces.বাংলা: উৎসেচক · हिन्दी: एंज़ाइम, which begin breaking the food into even smaller pieces your body can use. The bread turns sweet because an enzyme in saliva breaks its starchThe part of foods like rice, roti, bread and potatoes that gives you energy.বাংলা: শ্বেতসার · हिन्दी: स्टार्च into sugar.

So chewing is the first stage of digestion, and it matters. Food that is chewed well is already half-prepared when it reaches your stomach. That is why grown-ups say 'chew properly' — they are right.

Imagine a road that starts at your mouth and ends where waste leaves your body. Food travels along it in one direction. The road is really one long, soft tube, folded and coiled to fit inside you. Doctors call the whole thing the digestive systemAll the parts of your body that work together to digest food — one long tube from mouth to bottom, plus helpers like the liver.বাংলা: পরিপাকতন্ত্র · हिन्दी: पाचन तंत्र.

The stops, in order: the mouth (where chewing happens), the food pipeThe tube that carries food from your throat to your stomach. Its proper name is the oesophagus.বাংলা: খাদ্যনালী · हिन्दी: भोजन नली (a tube from your throat to your stomach), the stomach (a stretchy bag that churns food with juices), the small intestineThe long coiled tube after the stomach where nutrientsThe useful parts of food that your body keeps — for energy, for growing and for staying healthy.বাংলা: পুষ্টি উপাদান · हिन्दी: पोषक तत्व pass into your blood.বাংলা: ক্ষুদ্রান্ত্র · हिन्दी: छोटी आंत (a very long coiled tube where the useful parts of food pass into your blood), and the large intestineThe wide tube after the small intestine that takes back water and collects waste.বাংলা: বৃহদন্ত্র · हिन्दी: बड़ी आंत (a wider tube that collects water and the leftovers). Off to one side sits the liver, which makes a juice that helps digest fatty food.

The small intestine is the star. It is about six metres long in a grown-up — longer than a car — but it is coiled up so tightly that it fits in your belly. All that length gives food plenty of time and space to be absorbed.

Every bite you swallow makes this trip. It takes a long time — many hours from swallowing to the end — and most of it happens without you feeling a thing.

One thing to watch for: the food does not fall down. It is pushed. The walls of the food pipe, stomach and intestines are made of muscle, and they squeeze in waves, a bit like squeezing toothpaste along a tube. This squeezing is called peristalsisThe wave-like squeezing of the muscles in your food pipe, stomach and intestines that pushes food along.বাংলা: পেরিস্টালসিস (ক্রমসঙ্কোচন) · हिन्दी: क्रमाकुंचन, and it is why you can swallow while lying down, and why astronauts can eat in space where nothing falls at all.

Watch the small intestine especially. Tiny useful bits — nutrients — leave the tube and move into the bloodThe red liquid that flows all around your body, carrying nutrients and oxygen to every part.বাংলা: রক্ত · हिन्दी: रक्त. The blood then carries them to every part of you: your muscles, your brain, your growing bones. Everything else carries on to the large intestine.

This is not a test you can fail. It is a way to find out what has stuck. If you get a stop wrong, the amber marker shows you where — and one scroll up, the diagram and the animation are waiting for you to check.

A tip for remembering: think about what happens to the food at each stop. It gets cut (mouth), pushed (food pipe), churned (stomach), absorbed (small intestine), and dried out (large intestine). Cut, push, churn, absorb, dry.

Each stop on the road does one main thing, and the jobs are all different. The mouth cuts and softens. The food pipe pushes. The stomach churns and mixes with strong juices. The small intestine absorbs — it lets the nutrients out into the blood. The large intestine takes back water and collects waste. And the liverA large helper organ beside the stomach. It makes a juice for digesting fatty food and stores energy.বাংলা: যকৃৎ · हिन्दी: यकृत, on the side, makes a juice for fatty food.

If you can pair every part with its job, you understand digestion better than most grown-ups do. Tap a part on the left, then tap the job you think it does on the right. A letter appears to show your pair. Check when you are done — and change any pair marked amber.

Before you tap, try saying each meaning out loud in your own words. Then tap and compare. If you can explain a word to a friend, you know it — the exact wording does not matter.

Here is the whole chapter in one breath: digestion starts in the mouth with saliva and enzymes; the food pipe pushes food down by peristalsis; the stomach churns it; the small intestine absorbs the nutrients into the blood; the large intestine takes back water and collects the waste. Six ideas, one journey.