What Organs Make Up the Digestive System?

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The organs of digestion include the gastrointestinal tract, which is where all the action takes place and some accessory organs. It's one very long tube that starts at the mouth and ends with the anus. The accessory organs secrete various substances into the gastrointestinal tract that make the whole process easier. Here's a brief look at the organs of digestion:

Organs of the Gastrointestinal Tract

Oral cavity.

This is your mouth, and while it's not technically an organ, it's important because digestion begins in your mouth when you bite and chew your food, thus mixing it with saliva. The saliva (or spit) moistens food so that it's easier to swallow. It also contains a little bit of salivary amylase, a digestive enzyme that breaks down carbohydrates.

Pharynx. The pharynx is the portion of your throat where the back part of your mouth meets the esophagus and the trachea (your windpipe). As with the mouth, it's not technically an organ, but it is important. When you're done chewing food, your tongue pushes the food backward into the pharynx. A flap of tissue called the epiglottis shuts off the windpipe when you swallow so that food doesn't go down the wrong tube.

Esophagus. Once you swallow that bolus of food, it travels down the esophagus to the stomach. It's just a tube and not a complicated organ.

Stomach. Your stomach is a muscular bag-like organ. Cells in the stomach lining secrete gastric juices that break down proteins, and to a lesser degree fats, and a few other things. The muscles contract and squeeze the stomach contents to mix them with the juice. This changes the lumps of food you swallowed into a liquid substance called chyme.

Small intestine. The small intestine is where digestion finishes and absorption of nutrients occurs. Digestive enzymes break down the last bits of foods into the individual nutrients so they can be transported across the small intestinal walls and into the bloodstream. There are three parts to the small intestine called the duodenum, the jejunum, and the ileum.

Large intestine. By the time chyme reaches the large intestine, the nutrients have been absorbed, so the major function here is to absorb some of the water and prepare the leftovers for elimination as fecal material. It ends with the rectum and anus.

Accessory Organs of Digestion

Salivary glands. All that saliva has to come from somewhere, and that's what salivary glands are suitable for. You have three pairs of glands, the parotid, sublingual and submandibular glands, which are all connected to your mouth.

Liver. This is a very busy organ with lots of functions, but as far as digestion is concerned, it produces bile, which is secreted into the small intestine to help break down fats and oils.

Gallbladder. A small bag-like organ that stores the bile until it's necessary. It's a good thing to have a gallbladder, but you can live without one if necessary.

Pancreas. This organ makes digestive enzymes that break down carbohydrates, fats and proteins in the small intestine. It also secretes bicarbonates into the small intestine, which neutralizes the acidic pH of the chyme.

Brain and nose? You could argue the brain is an accessory organ since the mere thought of food can start the flow of saliva. In that way, your nose is important too, because smelling foods you like will also get your mouth watering. Having a jump-start of saliva does help digestion because it makes it easier to chew and swallow food.


Gropper SS, Smith JL, Groff JL. "Advanced Nutrition and Human Metabolism." Sixth Edition. Belmont, CA. Wadsworth Publishing Company, 2013.  8, 2016.

Smolin LA, Grosvenor, MB. "Nutrition: Science and Applications." Third Edition. Wiley Publishing Company, 2013.  

United States Department of Health and Human Services, National Digestive Diseases 
Information Clearinghouse (NDDIC). "Your Digestive System and How It Works." 

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