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The Digestive System: How Does It Work?

Medically reviewed by Regina Victoria Boyles, MD · Pediatrics

Written by Hello Doctor Medical Panel · Updated Oct 04, 2022

    The Digestive System: How Does It Work?

    What are the parts that make up the digestive system? Your digestive system is specially designed to convert the food you consume into nutrients that the body uses for energy, development, and cell repair.

    The digestive tract is made up of a single muscular tube that runs from the mouth to the anus. The mouth, pharynx (throat), esophagus, stomach, small intestine, large intestine, rectum, and anus are among the organs and parts of the digestive system that are crucial for processing food and liquids.

    Parts of the Digestive System


    The digestive process begins in the mouth when you chew. Your salivary glands produce saliva, a digestive juice, which moistens food so it moves more easily through your digestive tract. Chewing breaks the food into pieces that are more easily digested. Saliva mixes with food to start the process of breaking it down into a form your body can absorb and use.


    The throat, which is also known as the pharynx, is a component of the respiratory and digestive systems. It transports food, fluid, and air from the nose and mouth.


    The lower esophageal sphincter acts as a “valve” to prevent food from passing back into the esophagus. The esophagus is a muscular tube that extends from the pharynx to the stomach. It delivers food to the stomach through a series of contractions known as peristalsis.

    The esophagus is distinct from every other organ in the body because it is made up of both skeletal and smooth muscles. The upper part of the esophagus is entirely skeletal (2-4 cm). The middle is made up of both skeletal and smooth muscles. The lower part is about 11 cm long and entirely smooth. 


    The stomach is a sac-like organ with thick, muscular walls that mixes and breaks down food. It secretes powerful enzymes and acids that continue the process of digestion. The food then turns into the consistency of a liquid or paste and heads into the small intestine in small quantities. 

    Small intestines

    Comprised of the duodenum, jejunum, and ileum, the small intestines fulfills three key tasks. It breaks down food further, absorbs key nutrients, and gets rid of wastes.

    The following three organs are crucial in aiding the stomach and small intestine in food digestion:


    The oblong pancreas performs a variety of tasks, including secreting enzymes into the small intestine that digest the protein, fat, and carbs in our diet.


    The liver performs a variety of tasks. But the two key roles include producing and secreting bile and cleansing and purifying the blood leaving the small intestine.


    Bile is produced in the liver and then, if it has to be stored, travels through a passageway known as the cystic duct to the gallbladder. The gallbladder releases the bile into the small intestine when it contracts during a meal.

    Colon (large intestine)

    What remains of the food from the small intestine is passed to the large intestine, or colon, after the nutrients have been absorbed. The colon is a 5- 6-foot long muscular tube that is made up of the cecum, the ascending colon (on the right), the transverse colon (across it), the descending colon (on the left), and the sigmoid colon.

    Stools, or waste from the digestive process, are passed through the colon by means of peristalsis (contractions), first in a liquid state and then in solid form as the water is removed from the stool. Stool is stored in the sigmoid colon until it empties into the rectum once or twice daily. It typically takes stool about 36 hours to pass through the colon. The stool itself is mostly food debris and bacteria.


    The rectum is an 8-inch chamber that connects the colon to the anus. Its functions include receiving feces from the colon, alerting you when it’s time for bowel movement, and holding feces until they are expelled.

    When something (such as gas or stool) passes through the rectum, sensors send a signal to the brain that rectal contents need to be released. 


    The pelvic floor muscles form an angle between the rectum and the anus to prevent stool from coming out when it is not supposed to. The two anal sphincters (internal and external muscles); the upper anus’ lining, which is designed to detect rectal contents and tell us whether they are liquid, gas, or solid; and the pelvic floor muscles all work together to pass stool during bowel movement. 

    Learn more about the Digestive System here


    Hello Health Group does not provide medical advice, diagnosis or treatment.

    Medically reviewed by

    Regina Victoria Boyles, MD


    Written by Hello Doctor Medical Panel · Updated Oct 04, 2022

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