Your small intestine

Your small intestine is anything but small.  It is, in fact, a little skinnier but longer than your large intestine!  The average size of an adult’s small intestine is about 6.5 meters (that’s 22 feet!) and if you could spread it out, it would cover the same space as a tennis court! 

The main job of your small intestine is to break down the food you have eaten into pieces small enough to be absorbed by your cells.  The mouthfuls of food you eat have to be turned into pieces so small you could only see them with a microscope so remember to take sensible bites and to chew everything really well before you swallow it! 

The acid in your stomach is very strong and quite dangerous but your stomach has protection so it isn’t damaged by it.  When the food and acid mixture (chyme) travels from your stomach to your small intestine, it can put your small intestine in danger!  Luckily, bile from your liver mixes with the chyme to stop the acids working and protects the small intestine from acid burns.  Clever!

There are two main parts to your small intestine; the jejunum is in the middle of your small intestine and is where lots of chemicals called enzymes help to break down the food from your stomach into even smaller pieces.  Your small intestine has even more help to break down the chyme so that you can absorb its nutrients.  Enzymes from your pancreas help your body to digest fats and proteins from your food.  The bile from your live that stops acids from your stomach harming your small intestine is stored in your gallbladder until you need it.  All through your small intestine, everything works together as a team to make the whole system work!

Your ileum is the longest part of your small intestine and it joins your small intestine to your large intestine.  It is filled what look like lots of tiny folds called villi.  Imagine a folded piece of paper.  If you unfold it, you can see more of its surface.  These villi act in exactly the same way – the tiny folds mean there is more surface on your intestine for nutrients to be absorbed.  If your small intestine was just a smooth pipe, the food would pass through too quickly for it to absorb all of the nutrients.  Strong muscles in your small intestine push the food along.  As it moves past your villi, they make sure that every last nutrient is absorbed and that you get the most goodness from the food you have eaten.  Anything that isn’t of any use to your body is left behind and travels onto your large intestine!

Your food can spend up to about 6 hours in your small intestine before it enters your large intestine as a watery mixture.  During this time, your small intestine will have taken the most nutrients it can from the food you have eaten.  It is then up to your large intestine to absorb the very few last vitamins and minerals and return these to your body where they help you grow.  Remember to be good to your small intestine and eat good healthy food!