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Your body's waste disposal system

faeces; poo; waste; constipation; fibre; bowel; stomach; intestine; gastroenteritis; diarrhoea; ache; constipated; anus; rectum; digestive; system; toilet; urine; kidneys; bladder; wee; loo; dunny; lavatory; food; digestion; runs; lungs;


Why go to the 'loo'?

waste disposalWell, if we didn't go to the 'loo' regularly, we would have some very messy accidents!

Our bodies are like wonderful machines which process all the needed stuff that we take in, and then get rid of the waste - the stuff that we don't need.

As you know, this waste comes out when we go to the loo (or dunny, toilet, lavatory, or whatever you call it where you live).

The solid waste (faeces (fee-sees) or 'poo') is produced by your digestive system, and the liquid waste (urine or 'wee') is made by the kidneys.

How your digestive system works

  • When food goes into the mouth, it is chewed up into small pieces and water is added (saliva), so that everything can start sliding down the oesophagus (say uh-sof-er-gus), the tube that leads to the stomach.
  • The muscles in the oesophagus squeeze the food along. This squeezing action is called peristalsis (say perry-stal-sis).
  • In the stomach, acid is mixed with the food to continue digestion.
  • Next, the food is pushed into the small intestine (say in-tes-tine). This is the upper part of the bowel where some enzymes (say en-z-eye-mz) are added to help with digestion (not the same enzymes as those in washing powder!!).
  • Most food is turned into molecules, which are very small particles, ready to be sent to the other organs and body cells. These are absorbed through the wall of the small intestine into the blood, so that they can start on their journey to different parts of the body where they are needed. ('Absorbed' means like a sponge soaking up a liquid.)
  • Big bits that can't be absorbed through the wall of the small intestine go down into the lower bowel (colon).

What happens to the leftovers?

Water, some undigested bits of food and general body wastes now move to the lower bowel (the large intestine).

  • Bacteria (bak-teer-i-a) then join in to break some of this up and release some more nutrients like water and some vitamins, which are absorbed by the body.
  • The bacteria also make some gases, including hydrogen (say hi-drow-jen), methane (say me-thay-n) and hydrogen sulphide (hi-drow-jen sul-fide) (rotten egg gas). Some kids seem to have a lot of these gases, which sneak out quietly into the classroom and send kids, and teachers, rushing to open the windows!!
  • Everything that is now left over stays in the lowest part of the bowel, the rectum.
  • As more waste arrives, the nerves in the rectum let the brain know that it is time to empty this 'waste disposal' system.
  • When we decide to go to the loo, the anus opens and the muscles in the rectum push out the faeces.

Having the runs

having the runsSometimes you get sick and your poo goes all runny. You may get pains in your tummy and have to go to the toilet lots of times. This is called diarrhoea (say di-ah-re-ah).

Maybe you have got a germ making you sick, or maybe you have eaten something which had a poison in it (germs in the food can make a poison, or 'toxin'). Your body reacts to this bad stuff by pushing more water into your bowel, making your poo very soft and runny.

It is not very pleasant, and you may feel all hot and sweaty one minute and all shaky and cold the next.

So what can you do?

  • flush the toiletDrink plenty so that you don't get dehydrated. 'Clear fluids' are best. These are water, cordial or soft drinks with extra water in them, or special drinks you can buy from a pharmacy. Your parents might like to look at the topic 'Gastroenteritis' on the Child and Youth Health web site for information about clear fluids.
  • Stop eating for a day or so if you don't feel like having anything to eat.
  • Stay home (so that you don't give any germs to other people) and rest.
  • Mum or dad may take you to the doctor if you don't start feeling better soon.
  • Be careful to wash your hands really well after you've been to the loo and especially before you eat.

There is more about gastro in the topic 'Gastro - a tummy bug'.

Being constipated

being constipatedIf you can't do a poo when you feel like you want to, or your poo is really hard and doesn't want to come out, or it really hurts when it does, then you are probably constipated (say con-sti-pay-ted).

Some people do a poo every day, some do more than one poo every day, and others may go once every few days. We are all different, and only you know how often you usually need to do a poo. You are not constipated if your poo is soft, even if you don't do a poo every day.

Constipation (say con-sti-pay-shun) can be caused by lots of different things.

  • You may have waited too long to go to the toilet - perhaps if you are travelling or in a strange place.
  • being constipatedYou may be worried about using the toilets at school.
  • You may not have been drinking enough water.
  • You may not be getting enough fibre in your diet (our topic Eating healthy food will help you if you are not sure what this is).
  • You may not be getting enough exercise.
  • You may not be eating enough. I know that sometimes you want to rush out to play at recess or lunchtime and want to grab the best play area, but you should still eat your snacks and lunch.
  • Some medicines can make you constipated, and many people get constipated after they have been unwell.

How to keep regular habits

  • problems with toilets at schoolIf you are often constipated, then look at water, diet and exercise as the first things to change.
  • If you are having a really bad time with constipation, then mum or dad may get you something from the chemist to soften your poo to help you get started again - but you need to know that it is not a good idea to take this kind of medication very often.
  • If you are worried about going to the school toilets, then have a quiet talk with your teacher - you are probably not the only person who is worried, so something may need to be done.

Some people find this helps if you have tummy pain…
Rub your tummy in a circle from the top of your right leg, up to your ribs, across and down again, in the same direction that a clock's hands move - this may help to move things along, and can get rid of wind, if this is what is making you have pains in the tummy.

Your kidneys help too

While the blood is busily going round to all the parts of your body, it passes through the kidneys. The kidneys are so amazing that they really need a whole topic Your kidneys to tell you about them.

All we will say here is that the kidneys act as a sort of filter.

  • They catch lots of chemicals that are floating in your blood that your body no longer needs, or which could poison you if their level becomes too high.
  • They also remove extra water that is not needed by your body. This water helps flush the chemicals out through the kidneys.

This mixture of water and chemicals is called urine.

  • Urine is then sent on its way to the bladder, where it stays until your bladder feels full and sends a message to your brain.
  • Your brain tells you that you need to do a wee and off you go!

Even your lungs do it

You may wonder what lungs have to do with getting rid of waste. They breathe in air and breathe out the stuff that your body doesn't want from that air.

alcoholBut when we breathe out, we also get rid of other things, like carbon dioxide, which is made in our bodies, and some of the chemicals from our food and drink.

That is how breath-a-lysers can measure how much alcohol someone has been drinking. The amount of alcohol in a person's breath is a very accurate measure of how much alcohol is in their blood!

It is also how we can tell when someone has been eating fish or garlic (or smoking cigarettes - yuk, how bad does that smell?!)


Dr Kim says:

Dr Kim"Our bodies are wonderful. They organise themselves, but we are responsible for making sure that we help them to keep us healthy. A healthy diet and exercise will help our bodies to keep us active, and all the body systems working well".


Did you know?

In adults the small intestine plus the large intestine can measure up to 9 metres!!!
That's probably longer than your classroom!

Borborygmus (say bor-bor-ig-mus) is the name for that growling, glooping sound that you may sometimes hear coming from your insides. It's the sound of the food, liquids and gas working their way through your stomach and intestines. You may hear it when you feel hungry.

We make around 1.5 litres of saliva every day. That's a lot of spit!!! All of it gets swallowed so we don't get rid of waste by making saliva.

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We've provided this information to help you to understand important things about staying healthy and happy. However, if you feel sick or unhappy, it is important to tell your mum or dad, a teacher or another grown-up.


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