What is a Gastrointestinal Tract? Importance, Structure & Functions

gastrointestinal tract

The gastrointestinal tract is an empty muscular tube extending from the oral cavity, mouth, pharynx, esophagus, and stomach to the intestines. It proceeds to the rectum or anus. The GI tract is also known as the digestive tract or alimentary canal. It contains all the major organs that participate in food digestion. The digestive system in humans or all animals consists of large and small intestines and upper and lower gastrointestinal tracts.


These are slightly different in most animals. A human’s gastrointestinal tract also contains accessory organs, including the mouth, salivary glands, pancreas, liver, and gallbladder. The alimentary canal has three sections, the foregut, the midgut, and the hindgut. The digestive system is approximately nine meters long and contains more than four thousand different types of bacteria that regulate the body’s metabolism and immune system. In addition, they release hormones that help with digestion. These hormones include gastrin, secretin, ghrelin, cholecystokinin, etc.

Importance of digestion:

Digestion is a significant process. Our body needs energy, nutrients, proteins, carbohydrates, vitamins, minerals, fats, and water to work efficiently. Therefore when we eat something or drink, the digestive system breaks it down into nutrients that we need for body organs and to make hemoglobin for a healthy body. These waste products move out of the body.


The alimentary canal comprises of following organs: mouth, esophagus, stomach, small and large intestine, rectum, and anus (in order of functioning) with pancreas, liver, and gallbladder.

Here we examine how they work together?


The oral cavity, the mouth, is the starting point of the alimentary canal. Digestion begins the moment you bite. Even when you smell food, your salivary glands become active. When you start to chew, food breaks down into small pieces. Saliva in your mouth gets mixed with food, and the tongue pushes the food into the throat. Then into the esophagus.



In the throat, the esophagus receives swallowed food from the mouth. The esophagus is the part of the alimentary canal that joins the pharynx to the stomach. The epiglottis is small cartilage covering that prevents food from entering the windpipe. Esophageal Peristalsis is a set of muscular contractions that deliver food to the stomach. Furthermore, a circular-ring-like muscle gets its place at the bottom of the esophagus called the esophageal sphincter controls food flow in and out to prevent acid reflux and heartburn relates to the backward movement of food.



The stomach is a sac-like hollow structure between the esophagus and the small intestine. It is also best for food storage before it is processes further and for food distribution before entering the small intestine. It can store material up to1.5 liters.


Small intestine:

Small intestine

The small intestine is a tubular structure, 6 to 7 meters long, compose of the duodenum, jejunum, and ileum. The pancreas and liver provide enzymes that dissolve food, and Peristalsis also participates in this process by mixing the food with digestive enzymes from the liver and pancreas. The duodenum is responsible for the breakdown, and the other two are responsible for absorbing nutrients while the remaining residue moves to the large intestine. The ileum absorbs vitamin B12 & bile acids.


Digestive enzymes are secreted through the pancreas into the duodenum to break down carbohydrates, proteins, lipids, and fat. Besides producing insulin, the pancreas is also involves in sugar metabolism.



The liver is considered to be the chemical factory of our body. The liver secretes bile to dissolve nutrients absorb from the small intestine. Moreover, the liver detoxifies harmful enzymes produce within it that are harmful to the body.


Right below the liver on the right side of the abdomen, a pear-shape organ is present. It stores a yellowish-brown enzyme secreted from the liver. Its primary function is to deliver bile through the bile ducts into the intestine to help digestion.

Large Intestine:

The large intestine is a 1.5-meter-long tube known as the colon. Large intestines contain the cecum, rectum, anus, and appendix directly connect to the cecum. It is the last part of the gastrointestinal tract, and the colon is the most critical part of the large intestine. It is further divides into five parts; ascending, transverse, descending, and sigmoid. In this area, mineral ions such as sodium and chloride are reabsorb here. Seven hundred different types of bacteria present within the intestine are very effective in digestion. As a result, after intestinal absorption of nutrients, semi-solid waste material eliminates from the body through a bowel movement.


The digestive system performs the following significant functions in the body:

  • The digestive tract helps in the motility of food through the processes of ingestion, mastication, deglutition, and Peristalsis or segmentation.
  • It also helps with exocrine (bile consists of bicarbonates and enzymes) and endocrine secretion (hormones).
  • It refers to the breakage of food particles into smaller sub-units.
  • These end-products transfer to the bloodstream and lymphatic system through the alimentary canal.

How it Works:

The digestive tract is unique because it provides us with energy by converting the food we eat into nutrients. In fact, other waste materials discharge out of the body through the bowels.


The digestive system is the most crucial organ in the body, without which we cannot gain nutrients to grow. Therefore, the next time you have your meal, you can better understand where food is processed from beginning to end. A healthy digestive system plays a crucial role in maintaining a healthy body and ensuring the proper functioning of other body organs. Digestion is necessary for us to gain energy or nutrients.


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