Your large intestine

Your large intestine is almost the very last section of your digestive system.  It is tightly packed into your body, like the small intestine that comes before it, but it is a little fatter that the small intestine and a little shorter.  An adult’s large intestine, spread out, is about 1.5 meters (about 5 feet) long whereas an adult’s small intestine spread out is over 6.5 meters (that’s over 22 feet!) long.  You still have a little bit of growing to do before your large and small intestine get to those sizes, but they will!

Your large intestine has a very important job to do.  The main part of your large intestine is called the colon.  The food mixture (chyme) that travels from your stomach and through your small intestine doesn’t have very many nutrients left by the time it gets to your colon.  The chyme isn’t moved along by tiny hairs (villi) like in the small intestine, so it moves a lot more slowly.  Food can take 12 – 25 hours to travel through your large intestine, so the last nutrients from your dinner from Thursday are still being processed on Friday! 

The final digestion of nutrients like vitamins and minerals in your large intestine takes place with the help of over 700 different kinds of microbes, including our friend GI Jake, a Bifidobacterium!  As well as helping with digestion, these bacteria also produce small amounts of vitamins like vitamin B and vitamin K that your body uses to stay healthy.  Something else that bacteria produce that isn’t so welcome is gas!  The bacteria produce several gases including nitrogen, carbon dioxide and methane as they ferment undigested complex carbohydrates (like beans, breads and some vegetables!).  It’s a really good idea to chew your food properly so there is as few ‘lumps’ of these foods as possible in your large intestine and you don’t end up with mega-gas issues!  

In your large intestine, water and salts (like sodium) are taken from the chyme and returned to your body.  This is extremely important as it keeps your body balanced with the right amount of salt and water.  When the water is returned to your body, all that is left is the waste product – things your body doesn’t want or cannot use.  This waste doesn’t have much water and is compacted to become quite solid.  Some people call this waste poop or faeces, or a ‘stool’ or a bowel movement!  It has lots of different names but it all goes to the same place!  It passes from your large intestine, through your rectum and anus and is just flushed away!

Your large intestine also has a small diversion, like a little sock hanging out of the side.  This is your appendix.  Although your appendix is part of the digestive system, it doesn’t do very much for you.  In fact the only time we really remember it is if something goes wrong!  Sometimes an appendix may become infected which can be very painful.  If it is not treated, it can burst which can cause very serious problems.  In most cases, if an appendix gives any trouble, it is just removed.

All in all, your large intestine does a great job and you should really treat it properly by eating healthy foods, not eating late at night, not over-eating and chewing all of your food really well!  In the end, your large intestine will thank you!