We call it the gut, the colon, the intestines, the bowels and the digestive system. But what is it?
The gut, or digestive system, is in the abdomen.
The digestive system is for absorption of nutrients from food and expulsion of the waste.
The small intestine (or small bowel) is around 6 m long and roughly 2 cm wide.
On top of its many folds are forests of tiny finger-shaped protrusions called villae. Together, the folds and the villae make the gut's surface area as big as two tennis courts.
How it works
The digestive system works by propelling food through the intestines over 24 hours. Muscle contractions squeeze the food through the different sections of the intestine that are separated by bands of muscles, or sphincters, that act as valves.
The passage of food from one area of the intestines to another is coordinated so that food stays in a specific area for long enough for the gut to do a particular job - absorb fluids and nutrients, or process and expel waste.
The small intestine (small bowel)
Food passes from the stomach into the duodenum, which is the tube that leads from the stomach into intestines.
The food then passes through the ileum and jejunum before going to the colon (large bowel). The small intestine absorbs nutrients and much of the liquid from foods.
The colon’s main work is to store, process and expel waste. (The colon also absorbs some nutrients and water.) The rectum can store waste but most of the time it’s empty. Waste is expelled through the anus.
- Continence Foundation: Healthy Bowel
- US National Institute of Diabetes and Digestive and Kidney Diseases: Your digestive system and how it works
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