Key Organs of the Digestive System and Their Functions

Organs of the Digestive Tract

Have you ever wondered about the organs of the digestive system? Which organs make up the digestive system and what do they do? What is the function of the digestive system?

To help you understand more about the organs of the digestive system and their specific functions, let’s take a tour….


Our voyage through the digestive system starts at the beginning of the gastrointestinal tract: the mouth.

It may surprise you to know that digestion begins even before you take your first bite of a snack or meal. At the sight, Our Voyage through the Digestive System Starts at the Beginning of the Gastrointestinal Tract: the Mouth.     smell, sound or thought of food, your body begins preparing for the food that it anticipates is soon to arrive. This begins in the mouth where your senses trigger the salivary glands producing amylase, the enzyme that digests carbohydrates.

Once you place the food in your mouth, more saliva is added to the food as you grind the food by chewing. This softens the food, beginning the digestive process. It also keeps the mouth and teeth clean. Once the food is soft and relatively flexible, your tongue comes into play, pushing food to the back of your mouth at which point you swallow the food.


The next stop on our tour of the organs of the digestive system is the esophagus. This is a muscular pipe of around ten inches in length, which connects the mouth to the stomach. Soft food can travel down this tube in approximately six seconds. Dry food can take minutes. At the bottom of this passageway is a door-like barrier, known as the esophageal sphincter, which separates the esophagus from the stomach. This barrier remains closed most of the time but is triggered to open by the action of swallowing.


On leaving the esophagus the food enters your stomach. This is a j-shaped muscular pouch, which has two specific functions:

  • Storage: providing a container for the food and liquid you swallow.

  • Processing: The stomach is like a food processor or blender, which uses its muscles to chop and mix food with acid, water and yet more digestive enzymes. Over a period of several hours, it liquefies the food into a thick fluid known as chyme, which is then slowly emptied into the small intestine.

Your stomach is also key for protein digestion – it uses hydrochloric acid and the powerful enzyme pepsin to begin the process of breaking down proteins such as milk, eggs, meat and cheese.

Small Intestine

Now we come to the small intestine, a tube-like structure, which rather confusingly is not at all small! In fact in a mature adult the small intestine is around twenty-one feet long. It’s coiled up inside your body but if it were spread out flat, its surface would cover an entire tennis court!

As a whole the small intestine is responsible for nutrient, water and electrolyte absorption. It comprises three joined areas, which each perform different elements of this task. Have a look at our bullet list below to learn all about the sub-sections of the small intestine:

The Small Intestine is One of the Main Organs of the Digestive System

  • Duodenum: this is the first and shortest segment of the small intestine totaling around 12 inches in length. Its function is to receive and neutralize the partially digested acidic food, the chyme, from the stomach. It also adds digestive juices from the liver, pancreas and gallbladder to the chyme, and mixes the content, carrying out most of the chemical digestion that occurs in the small intestine. Some absorption of nutrients also occurs in the duodenum including calcium, copper, iron, folic acid, manganese, zinc as well a vitamins A and B2.

  • Jejunum: this is the middle section of the small intestine, stretching between four and seven feet in length. Here the process of digesting your food is completed. It’s also the part of the small intestine where the majority of nutrients are absorbed.

  • Ileum: Last but not least we come to the final but longest section of the small intestine, the ileum. At around 13 feet long, its main task is to absorb vitamin B12 and to re-absorb bile, the latter being returned to the liver through blood vessels and the intestinal wall. The ileum also acts as a back up, absorbing any nutrients that were not taken in by the jejunum. It is this part of the digestive tract which is most commonly inflamed in Crohn’s Disease and thus is for many sufferers where the symptoms of Crohn’s Disease emanate.

Large Intestine

The next stop on our voyage of the organs of the digestive system is the large intestine or large bowel. This is divided into the ascending colon, on the right of your body, the transverse colon, which lies horizontally across your belly under your ribs, and the descending colon to your left. Together these sections of the large intestine complete the process of digestion. Tube-like in structure, the large intestine measures around five feet in length. Its main tasks are:

  • Absorption of vitamins (notably B vitamins and vitamin K), which are made by your friendly colonic bacteria.

  • Waste storage and disposal: the transverse colon processes and forms stools which are then stored in the descending colon and when enough have collected, they are they are expelled from your body by defecation.

Accessory Digestive Organs

As well as these main digestive system organs, you also have some additional organs, known as accessory organs. Though these organs do not form part of the main digestive tract, they are key to the digestive process. These organs ensure that the functions of the digestive system can take place. Without them your system would simply not work.

The accessory organs of the digestive system are the liver, the pancreas and the gallbladder.


This is a vital multi-functional organ. Its digestive functions include:

  • Manufacturing and releasing a substance called bile, which is essential for digesting fats.

  • Processing carbohydrates and proteins.

  • Breaking down food from the intestines and turning it into energy.

  • Storage of sugar in the form of glycogen, which it quickly converts back to sugar to provide energy quickly .

  • Storage of vitamins and iron and other essential chemicals.


The pancreas is a gland, which you probably know best for its role in producing insulin. However it also plays an essential role in digestion as one of the accessory organs of the digestive system. Its job is to release pancreatic juices, which contain digestive enzymes. These enzymes help break down the fats, proteins and carbohydrates in the pre-digested food in your small intestine.

The Gallbladder

The Pancreas and Gallbladder are Accessory Organs of the Digestive System

The last stop on our whistle-stop tour of the organs of the digestive system is the gallbladder. Tucked underneath your liver, this small organ stores the bile, which is made by your liver. It also works on the bile making it more potent and more effective. When you eat, the liver and gallbladder release bile via a small tube like structure, known as the common duct, into the small intestine where it processes the fat in the partially digested foods.

As you have learned on our mini-guide to the organs of the digestive system, there are many organs involved in digestion, each with its own specific role and each key to the process as a whole.

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