Healthdirect Free Australian health advice you can count on.

Medical problem? Call 1800 022 222. If you need urgent medical help, call triple zero immediately

healthdirect Australia is a free service where you can talk to a nurse or doctor who can help you know what to do.

The digestive system breaks down food into nutrients.

The digestive system breaks down food into nutrients.
beginning of content

Digestive system

Your digestive system breaks down the food you eat into nutrients such as carbohydrates, fats and proteins. They can then be absorbed into your bloodstream so your body can use them for energy, growth and repair. Unused materials are discarded as faeces (or stools).

Your digestive system starts at your mouth, then your oesophagus, stomach, small intestine, large intestine and anus. These organs are the specialised parts of a long, twisting tube called the digestive tract.

Other organs that form part of the digestive system are the pancreas, liver and gallbladder.

What is the digestive system?

Each organ of the digestive system has an important role in digestion.


When you eat, your teeth chew food into very small pieces. Glands in your cheeks and under your tongue produce saliva that coats the food, making it easier to be chewed and swallowed.

Saliva also contains enzymes that start the digestion of the carbohydrates in your food.


Your oesophagus is the muscular tube that carries food from your mouth to your stomach after you swallow. A ring of muscle at the end of the oesophagus relaxes to let food into your stomach and contracts to prevent stomach contents from escaping back up the oesophagus.


Your stomach wall produces gastric juice (hydrochloric acid and enzymes) that digests proteins. The stomach acts like a concrete mixer, churning and mixing food with gastric juice to form chyme – a thick, soupy liquid.

Small intestine

Bile from your gall bladder and enzymes in digestive juices from your pancreas empty into the upper section of your small intestine. These help break down protein into amino acids and fat into fatty acids. These smaller particles, along with sugars, vitamins and minerals, are absorbed into the bloodstream through the wall of your small intestine.

It is called small because it is about 3.5cm in diameter but it is about 5m long to provide lots of area for absorption. Most of the chemical digestion of proteins, fats and carbohydrates is completed in your small intestine.

Large intestine and anus

The lining of your large intestine absorbs water, mineral salts and vitamins. Undigested fibre is mixed with mucus and bacteria – which partly break down the fibre – to nourish the cells of the large intestine wall and so help keep your large intestine healthy. Faeces are formed and stored in the last part of the large intestine (the rectum) before being passed out of the body through the anus.

Common conditions related to the digestive system

Gastro-oesophageal reflux

Gastro-oesophageal reflux (GORD) occurs when acidic stomach contents moves from the stomach back up the oesophagus. It causes a burning sensation in the chest or throat.


Diverticulitis is a sometimes painful condition caused by inflammation or infection of abnormal pouches in the lower part of the large intestine.

Stomach ulcers

Stomach ulcers are caused by the bacterium Helicobacter pylori that can live in the stomach of about 4 in 10 Australians. They can cause long-term, low-level inflammation of the stomach lining in some people. Why they cause stomach ulcers in some people and not others is not well understood.


Haemorrhoids are itchy or painful lumps that occur in and around your anus. The lumps contain swollen blood vessels. If you find blood on the toilet paper or in the toilet, always seek medical advice.

Last reviewed: May 2017

Need more information?

These trusted information partners have more on this topic.

Found 1711 results

Digestive system

Find health conditions articles related to the digestive system.

Read more on WA Health website

Digestive system

The digestive tract can be thought of as a long muscular tube with digestive organs attached along the way.

Read more on Better Health Channel website

A guide to irritable bowel syndrome Dietitians Association of Australia

A guide to irritable bowel syndrome Irritable bowel syndrome (IBS) is a condition of the digestive system that may result in a variety of uncomfortable symptoms

Read more on Dietitians Association of Australia website

Kids' Health - Topics - Intestines - your guts!

The intestines are part of the digestive system of the body. They are sometimes called the guts or bowels. This system deals with all the food and drink that you take into your body. You can learn more about the digestive system in the topic 'Your waste disposal system'.

Read more on Women's and Children's Health Network website

How your food is digested -

The digestive system is a series of hollow organs such as the stomach and small intestine. Digestion starts in the mouth with the production of enzymes to break down carbohydrate and then moves to the oesophagus. 

Read more on myDr website


Peritonitis Category: Digestive Health Topic: Signs and Symptoms of the Digestive System Send by email View as PDF Send by post Peritonitis is inflammation of the membranes of the abdominal wall and organs

Read more on Queensland Health website

Probiotics | Women's Health Queensland Wide

Probiotics are a hot topic at the moment. We explain what they are and why they are good for you.

Read more on Women's Health Queensland Wide website

Laparoscopic gastric bypass

A gastric bypass (also called Roux-en-Y) involves stapling your stomach to create a smaller stomach ‘pouch’ and then bypassing the rest of your stomach and part of your bowel (see figure 1). It works by making you feel full sooner so that you eat less, and by preventing some of the calories and nutrients in your food from being absorbed.

Read more on Better Health Channel website

Kids' Health - Topics - The digestive system - powering up your body

Machines need a power source in order to work. Your body is like a very complicated machine and it needs power to be able to work properly too. Food provides the fuel to give your body the power it needs.

Read more on Women's and Children's Health Network website


Gastroenteritis, commonly called gastro, is an infection or inflammation of the digestive system.

Read more on WA Health website

Healthdirect 24hr 7 days a week hotline

24 hour health advice and information you can count on

1800 022 222

Government Accredited with over 140 information partners

We are a government-funded service, providing quality, approved health information

Australian Government, health department logo ACT Government logo New South Wales government, health department logo Northen Territory Government logo Government of South Australia, health department logo Tasmanian government logo Government of Western Australia, health department logo