Organs and Function of the Digestive System

The digestive system consists of several organs that function together to break down the foods you eat into molecules your body can use for energy and nutrients. The digestive tract includes the mouth, esophagus, stomach, intestines, and anus. So-called "accessory" organs include the liver, pancreas, and gallbladder; food doesn't move through these organs, but they secrete hormones and chemicals that are essential to digestion. Here's what to know about your digestive system organs and functions.

The Mouth

Boy sticking out tongue — WIN-Initiative / Getty Images

Digestion begins in your mouth. Your teeth grind the food you eat and mix it with saliva to form a kind of ball, known as a bolus.

During the mixing, an enzyme called salivary amylase starts breaking down carbohydrates. Once the food is soft and relatively flexible, the tongue pushes it to the back of your mouth and into the esophagus.

The Esophagus

Human esophagus and stomach — SEBASTIAN KAULITZKI/SCIENCE PHOTO LIBRARY / Getty Images

Your esophagus is a flattened muscular tube that connects your mouth to your stomach. As food is swallowed, your esophagus expands. It takes food about three seconds to pass through your esophagus, depending on the texture and consistency.

Common problems of the esophagus include heartburn, acid reflux, and gastroesophageal reflux disease (GERD), which are caused by acid flowing up from the stomach and irritating the lower part of the esophagus.

The Stomach

Woman Holding Illustration of Stomach — Toshiro Shimada / Getty Images

Your stomach is a J-shaped muscular pouch, which receives food from your esophagus and sends it to your small intestine. Inside your stomach, food is mixed with enzymes and acid until it becomes a liquid, called chyme.

The stomach is the main site for protein digestion and uses powerful enzymes, known as pepsins, as well as hydrochloric acid, to digest foods like meats, milk, and cheese.

The Small Intestine

Illustration from Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013. — OpenStax College / Wikimedia Commons / CC-BY-3.0

The small intestine is an approximately 20-foot-long muscular tube, which is divided into three distinct parts: the duodenum, the jejunum, and the ileum. Each of the three parts plays a major role in digestion and absorption.

Absorption is a crucial part of the digestive process that brings the molecules from the digested food into the blood and, ultimately, the cells.

Problems with your small or large intestine can affect the way your body absorbs and digests food, leading to malnutrition. People who are missing parts of their intestines or have limited intestinal mobility may require total parenteral nutrition (TPN), a type of nutrition that bypasses the digestive system.

The Large Intestine

Male large intestine anatomy, illustration — PIXOLOGICSTUDIO/SCIENCE PHOTO LIBRARY / Getty Images

The last part of the digestive tract, the large intestine, is a muscular tube that is about 6 feet long. It's divided into the cecum, the colon, and the rectum. Together, these segments complete any nutrient absorption and process the waste into feces.

Problems with your large intestine can be caused by diseases such as inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative colitis as well as celiac disease. If parts of these organs become seriously diseased, they may require surgical removal. When this happens, an ostomy may be necessary to aid digestion and elimination.

The Anus

The anus is the last organ of the digestive system. It is a 2-inch long canal consisting of pelvic floor muscles and two anal sphincters (internal and external) which allow you to hold in feces until you are able to get to a bathroom to release the contents into the toilet.

The Pancreas

The pancreas is one of the three "accessory" digestion-related organs. Your pancreas assists your small intestine by secreting pancreatic juice, a liquid filled with enzymes and sodium bicarbonate that is able to stop the digestion process of pepsin. It also secretes insulin, which helps your body regulate your blood sugar.

The Liver

Male liver and pancreas, illustration — PIXOLOGICSTUDIO/SCIENCE PHOTO LIBRARY / Getty Images

Your liver has many functions. First, it produces bile, which the small intestine uses to help digest the fats in food.

It also metabolizes proteins, carbohydrates, and fats; helps regulate blood sugar levels; stores glycogen for quick energy; makes fibrinogen, which clots blood; makes vitamin A; and recycles worn-out red blood cells.

Diseases of the liver, such as hepatitis, can have major complications that affect other parts of the body as the liver is involved in so many essential functions, like digestion.

The Gallbladder

Tucked under the liver, your gallbladder is a storage container for bile, a yellow-green fluid made up of salts, cholesterol, and lecithin. Your small intestine uses bile to digest fats.

Most people never think about their gallbladder until a problem with gallstones or gallbladder disease, such as cholecystitis, develops. If you have a gallbladder-related disease, you may experience jaundice.

This happens when the bile cannot leave the gallbladder. Instead, the bile enters the bloodstream, which can cause your skin, eyes, and nails to appear yellow.

Frequently Asked Questions (FAQs)

What are the accessory organs in the digestive system?

The pancreas, liver, and gallbladder are considered accessory organs. Food does not move through them, as it does in the gastrointestinal tract, but these organs release hormones and chemicals that are essential to digestion.

How are digestive system organs affected by type 1 diabetes?

In type 1 diabetes, your pancreas does not produce insulin, causing your blood sugar to rise. Another digestive complication of type 1 diabetes is gastroparesis, in which it takes longer than usual for the stomach to empty its contents into the small intestine.