What is the path food takes through the digestive system

What is the path food takes through the digestive system

If you have a digestive condition, you may know a lot about a single part of your digestive system. However, you may not know how each part of the digestive system works together to help us digest and absorb the food we eat.

The digestive system is made up of the gastrointestinal tract (AKA the GI Tract) and the liver, pancreas, and gallbladder.

Below you will find an overview of the parts of the digestive system.

What is the path food takes through the digestive system
Source: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.

Mouth

The mouth is the first point of contact between food and our digestive system. Food enters the mouth and our teeth grind the food into smaller pieces, while our saliva starts breaking down carbohydrates. Our tongue pushes the food to the back of our throat so it can then be swallowed.

Esophagus

Food is then swallowed and enters the esophagus. A contraction and relaxation of muscles pushes the food along the esophagus in a wave-like motion called peristalsis.

Stomach

Next, food enters the upper part of the stomach and is mixed with digestive juices. The contents of the stomach (called chyme) are then slowly emptied into the small intestine.

Small intestine

The small intestine is the main site of vitamin and nutrient absorption along the digestive tract. Digestive juices made by the pancreas, liver, and intestines help to break food down into components that are small enough to pass through the intestinal wall to be used by the body. Water is also absorbed by the small intestine.

Pancreas

The pancreas makes a digestive juice that contains enzymes which break down proteins, carbohydrates, and fats. These digestive juices flow from the pancreas into the intestines via a tube called a duct.

Liver and gallbladder

The liver makes a digestive juice called bile. Bile helps us break down fats and plays an important role in the absorption of fat-soluble vitamins (such as Vitamin D). Bile is stored in the gallbladder between meals and is released into the intestines via the bile duct.

Large intestine

Food continues to be pushed through the small intestine and into the large intestine (AKA the colon) by peristalsis. Most of the remaining water is absorbed at this point along with electrolytes and certain vitamins.

The large intestine is also the site of a collection of microbes called the “microbiota”. This includes bacteria which ferment (break down) certain types of carbohydrates and make gas and other byproducts.

Rectum

The very end of the large intestine is called the rectum. It is the end of the line for the intestinal contents where stool is stored and pushed out during a bowel movement.

For a detailed look at how food moves through our digestive system system, check out this video.

Katelyn Collins, RD is a registered dietitian specializing in irritable bowel syndrome (IBS) and digestive health. Katelyn’s personal experience with IBS first sparked her passion for nutrition and health. Since then, she has been a vocal advocate for the digestive health community and has dedicated her own nutrition practice to serving those with digestive conditions.

Your digestive system is made up of a series of organs that allows your body to get the nutrients and energy it needs from the food we eat.  As food travels through the digestive system it is broken down, sorted, and reprocessed before being circulated around the body to nourish and replace cells and supply energy to our muscles. 

Digestion starts in the mouth where chewing and saliva breaks down food so it is more easily processed by your body. 

Esophagus: The esophagus is a muscular tube that connects the pharynx (throat) to the stomach. The esophagus contracts as it moves food into the stomach. A “valve” called the lower esophageal sphincter (LES) is located just before the opening to the stomach. This valve opens to let food pass into the stomach from the esophagus and it prevents food from moving back up into the esophagus from the stomach. 

Medical conditions related to the esophagus:

  • Barrett’s Espohagus
  • Dysphagia (Difficulty Swallowing)
  • Eosinophilic esophagitis (EoE)
  • GERD

Stomach:  An organ with strong muscular walls, the stomach holds the food and mixes it with acid and enzymes that continue to break the food down into a liquid or paste.  

Small Intestine (Small Bowel): Almost 20 feet long, the small intestine is the workhorse of the digestive system. It will continue to break down food with enzymes released by the pancreas and bile released from the liver. It is made up of three segments, the duodenum, which continues the breakdown of food; and the jejunum and ileum, which are mainly responsible for the absorption of nutrients. 

Medical conditions related to the small bowel:

  • Polyps, Tumors and Malabsorptive Diseases in the Small Bowel

Pancreas: Your pancreas is located behind your stomach and is attached to both your gall bladder and your small intestines. Among other functions, the pancreas aids in digestion by producing digestive enzymes and secreting them into the duodenum (the first segment of the small intestine).  These enzymes break down protein, fats, and carbohydrates.

Medical conditions related to the pancreas:

  • Ampullary Polyps and Cancer
  • Pancreatitis

Liver: An organ with many functions, your liver’s two main responsibilities in the process of digestion are to make and secrete bile and to process and purify the blood containing newly absorbed nutrients that are coming from the small intestine. Bile has two main purposes: to help absorb fats and to carry waste from the liver that cannot go through the kidneys. 

Medical conditions related to the liver:

  • Cirrhosis of the Liver
  • Fatty Liver Disease (Non-Alcoholic)
  • Hepatitis (Viral)
  • Liver Disease and Hepatology
  • Wilson’s Disease

Bile Ducts:  Bile made in the liver travels to the small intestine through the bile ducts.  If the bile isn’t needed immediately, it is stored in the gallbladder.

Medical conditions related to the bile ducts:

  • Ampullary Polyps and Cancer
  • Bile Duct Leaks
  • Bile Duct Stones    

Gallbladder:  A pear-shaped reservoir located just under the liver that receives and stores bile made in the liver.  The gallbladder sends this stored bile into the small intestine to aid in the digestion of food.

Colon (Large Intestine):  A 5- to 7-foot-long muscular tube that connects the small intestine to the rectum and is responsible for processing waste so that defecation is easy and convenient.  It is made up of the ascending (right) colon, the transverse (across) colon, the descending (left) colon and the sigmoid colon, which connects to the rectum. 

Medical procedure related to the colon:

  • Colonoscopy

Rectum:  An 8-inch chamber that connects the colon to the anus.  The rectum receives stool from the colon, sends signals to the brain if there is stool to be evacuated, and holds stool until evacuation can happen.

Anus:  The last part of the digestive tract, the anus, consists of pelvic floor muscles and two anal sphincters (internal and external).  Together their jobs are to detect rectal contents, whether they are liquid, gas or solid, and then control when stool should and shouldn’t be excreted from your body. 

University of Michigan program related to the anus:

  • Michigan Bowel Control Program

Medical Conditions Involving Multiple Digestive Organs

There are many medical conditions that involve more than one digestive organ. These include:

  • Inflammatory Bowel Disease (IBD), which includes Crohn's disease and ulcerative colitis
  • Irritable Bowel Syndrome (IBS)
  • Diarrhea
  • Constipation