Your digestive system

What happens when you down your dinner or savour a snack?

Your food goes on a remarkable journey, starting with that first bite, and all thanks to your digestive system.

So, what is digestion, and how does it work?

Put simply food gives the cells in your body the energy and nutrients they need for growth and repair. But the cells cannot use the food in its original state, it needs to be broken down and processed – this process is called digestion.

In a nutshell, your mouth chews and breaks down food into little pieces. Then chemicals in your gut called enzymes turn complex nutrients into simple ones. Your bloodstream absorbs these nutrients from your gut and takes them to the cells. Food that remains undigested and not needed by the body is dumped as waste when you go to the toilet.

Digestion takes place in many different parts of your body and your digestive organs. Here are the parts of your body involved:

Digestive organs

A long tube called the alimentary canal (your gut) forms the main part of your digestive system. It runs from your mouth to your anus. It’s made up of the mouth, oesophagus (food pipe), stomach, small intestine and large intestine. Your teeth, tongue, salivary glands, liver, pancreas and gall bladder are all attached to the alimentary canal, and they all help out with digestion.

• Oesophagus
  This travels down behind the heart, taking food that you have chewed from the throat to your tummy.
• Stomach
  Your tummy churns the food, turning it into a creamy mixture and starts to digest some of the protein in your food.
• Gall bladder
  This provides bile that helps in the digestion of fatty foods.
• Pancreas
  This supplies most of the enzymes that you need to digest your food.
• Small intestine
  Most of the process of digesting carbohydrates, fats and protein in foods takes place here and the nutrients are then absorbed.
• Large intestine
  This absorbs water and salt and then gets rid of waste.
• Liver
  This processes the nutrients that have been absorbed.
• Rectum
  This is the end of the large intestine and waste (also known as stool, poo, or faeces) is stored here until you are ready to go to the toilet. The anus is the final part of the rectum. 

The process

Food is ground up by the teeth and mixed with saliva by the tongue. The salivary glands squirt the saliva (which contains an enzyme to start digesting starchy food) into the mouth when you’re chewing. This also makes the food easier to swallow and stop it from scraping on the way down.

The food is carried down your oesophagus to the J-shaped stomach – this is the widest and most stretchy part of the alimentary canal.  Here it is churned by the muscular walls, where acidic digestive juices mix with the food. The resulting creamy liquid is called chyme (pronounced kime). Food spends about three hours in your stomach. It then leaves through a funnel-shaped exit and enters the small intestine. This is about six hours after your first mouthful.

Your gall bladder sends a jet of bile through its duct into the small intestine. This breaks up fat into tiny droplets that are much easier to digest. Equally as important, the pancreas release pancreatic juice through its own duct with super-powerful enzymes to help break the food down further.  In the small intestine all the useful nutrients are absorbed into your body. They make their way through the wall of the intestine into your blood.

Any undigested waste from the small intestine reaches the large intestine (the beginning of the colon) and leftover nutrients like water and salts are absorbed. The rest of the waste dries out to form faeces, which sit in the rectum until they are excreted from the body, and the process comes to a natural end!”

Normally faeces get to the rectum between 24 and 48 hours after you swallow your food.

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