Bowel health

The digestive system

An overview of how we get nutrition and eliminate waste, and how long food takes to pass through each part.

1. 1MouthChewing takes up to one minute.
2. 2EsophagusAbout three seconds to swallow.
3. 3StomachFood stays for 1 to 3 hours.
4. 4Small intestineAbout 2 to 6 hours. By the end, food is fully digested.
5. 5Large intestine12 to 48 hours, as most of the water is absorbed.
6. 6RectumStool and gas are stored here until they leave through the anus.

How we get nutrition and how we eliminate waste is usually taken for granted until there is a problem. The digestive system begins at the mouth and ends at the anus. Here is an overview of its parts and how each works.

Mouth

Ingests food and fluid, breaks food down by chewing, and begins digestion by adding saliva.

Esophagus

This tube carries food and fluid to the stomach.

Stomach

Breaks down and mixes up food and holds it until the bowel is ready for it (up to two hours). It can hold one liter of food and fluid, and we feel full at about half a liter.

Gastrocolic reflex

Starts waves of movement that carry digested food onward toward the rectum 3 to 6 times a day.

Small intestine (small bowel)

Includes the duodenum, where most digestion takes place because of added secretions from the pancreas, gallbladder, and liver, followed by the jejunum and ileum. Food takes 4 to 6 hours to pass through this section.

Colon (large intestine)

Receives 1,000 to 1,500 ml of digested food per day, now a thick liquid. It has three parts: the ascending, transverse, and descending colon. Transit time through the colon to the sigmoid (storage) section is 24 to 72 hours depending on what has been eaten, and fatty meals take longer. It passes hardened feces on to the rectum.

Rectum

Once stool enters the rectum, we become aware that we need to have a bowel movement.

How food passes through the digestive system

1. MouthFood is chewed, which takes up to one minute.
2. EsophagusFood is swallowed, taking three seconds to pass through.
3. StomachDigestion starts here, and food stays for 1 to 3 hours.
4. Small intestineLiquefied food takes about 2 to 6 hours to travel through. By now it is fully digested.
5. Large intestineBy the end of its stay of 12 to 48 hours, most of the water content has been absorbed.
6. RectumStool and gas are stored in the rectum until they are expelled through the anus.