KS2 Digestive System: Everything You Need To Know

A family are sat at the table together sharing a meal, the salad they are eating will travel through the digestive system.

Image © freepik, under a Creative Commons license.

We eat food every day without a second thought, but the whole process is really quite amazing when you think about it.

The human digestive system is part of the National Curriculum for primary school children in Year 3, Year 4 and Year 5. They are bound to come home with lots of questions about the process and, thanks to our handy guide, now you can have all the answers!

There is so much more to learn about the human body. Once your kids have perfected their knowledge of the digestive system, they can take a look at these brilliant respiratory system facts, or see how many of these science trivia questions they can answer - good luck!

KS2 Digestive System: What Does It Do?

When we eat food, the body needs to break it down so that our bodies can use substances from it. This process is called digestion. The digestive system is the name for the series of organs that work together to help break down food the food that we eat so that we can absorb it into the bloodstream.

A close up image of a little boy eating raspberries that will travel through his digestive system.
Image © nastyaofly, under a Creative Commons license.

Digestive System KS2: How Does The Human Digestive System Work?

Eating food is second nature to most of us - especially little children with hungry tummies! We don't tend to think much about how we digest food, so prepare to amaze your child by talking through the five stages of digestion with them.

1) At the beginning of the process, food enters the digestive system via the mouth. Here, we use our teeth to crush and chew the food. It's also mixed with saliva so it's easier to swallow.

2) Next, the food is pushed down a long tube called the oesophagus and then goes into the stomach.

3) Here's where it gets interesting. The stomach produces strong acid called hydrochloric acid - this kills microorganisms, which may have been swallowed with the food and can be harmful.

Enzymes are also produced in the stomach, These do the crucial job of breaking down food so it can be absorbed into the body.

The food is now partially digested and enters the intestines.

4) The intestines are split into two parts - the small intestine and the large intestine.

Digested food is absorbed into the small intestine first. It passes through the wall of the small intestine and absorbed into the bloodstream. The blood carries the useful substances from the food around the body.

Most of the digested food has been absorbed by the time it reaches the large intestine, so what's left isn't needed or can't be digested by the body.

5) This waste material is called faeces or poo, and it's stored in the rectum until we're ready to go to the toilet.

A close up image of a woman smiling as she eats a bowl of cereal representing the beginning of the digestive system.
Image © nensuria, under a Creative Commons license.

Digestive System Facts

Want to geek out with your child with even more facts on the digestive system? Here's our top 10:

1) Saliva is used at the start of the digestive process. We make one to three pints of this a day!

2) An adult's stomach can handle 1.5 litres of material.

3) Food stays in our stomachs for three to four hours.

4) The hydrochloric acid produced by the stomach to kill off harmful bacteria is also found in cleaning supplies including toilet bowl cleaners - it's strong stuff!

5) The stomach has a thick coating of mucus to protect itself from this corrosive acid. The stomach has to produce a new coat of mucus every two weeks.

6) When your tummy rumbles, it's the sound of normal movements in your stomach and intestines as food, gas and fluid pass through the gastrointestinal tract. However, when the tract is empty, there's nothing there to muffle the sound so it makes a loud noise.

7) The small intestine is about seven metres long and 2.5 centimetres in diameter. The surface area is a huge 250 square metres - about the size of a tennis court!

8) There are more than 400 species of bacteria in the colon.

9) Enzymes, which are found in the human digestive system, are also present in washing detergents to get dirt out of clothes.

10) There are three types of enzymes used in the digestive system. Proteases help to break down meat, amylases help to break down carbohydrates and lipases help to break down fats. Your saliva contains amylases and lipases while proteases are used in the stomach and intestines.

Glossary Of Digestive System Terms

The information above should cover the digestive system for kids, but for inquisitive minds (both adults' and children's) here's a more comprehensive list of human digestive system terms and organs:

Absorb: To take in nutrients or chemicals.

Bacteria: A single-celled microorganism. Some species are responsible for illness.

Colon: This is another word for the large intestine.

Corrosive: The ability to destroy something with a chemical action.

Digestive tract or gastrointestinal tract: These are the parts of the body that break down food - the mouth, oesophagus, stomach, pancreas, liver, gallbladder, small intestine and large intestine.

Enzyme: A complicated chemical produced by living cells.

Excrete: To get rid of the waste generated (in other words, when we poo).

Large intestine: Here, water is absorbed from undigested food.

Liver: This organ produces bile which helps with the digestion of fat.

Mouth: At the start of the digestive process, food is chewed in here and mixed with saliva.

A young girl is sat cross legged on the floor of a library reading a book, she is learning about the digestive system.
Image © rido81, under a Creative Commons license.

Mucus: A clear, slimy, lubricating substance.

Nutrient: A substance that provides nourishment (so the good stuff that's in our food).

Oesophagus: Food is squeezed down here from the mouth into the stomach.

Organ: A complete or independent part of a human or animal that has a specific job to do.

Pancreas: This organ produces additional enzymes to help digest food.

Rectum: This is where the faeces is stored before it's ready to leave the body.

Saliva: A clear liquid secreted into the mouth by salivary glands, consisting of water, mucin, protein and enzymes.

Stomach: This is a bag with strong muscles. It mixes food with acid and begins to break it down.

Secrete: To produce and discharge a substance.

Small intestine: Where food is broken down and nutrients are absorbed.

You can help your child learn about the digestive system by drawing a diagram of the body and pointing out where each part of the digestive system is, or you could point to some of them on your own bodies. Why not see how many your child can identify on a diagram first and then help them to work out the rest together?



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