Food fulfills a higher purpose than tantalizing your taste buds or producing a full and satisfied feeling in your belly. Your body breaks down the foods and beverages that you eat into tiny particles that it can absorb. The villi, located in the small intestine, play a vital role in digestion by increasing your body’s ability to absorb nutrients. To understand the role of the villi, you need to explore the process of digestion, the role of the small intestine and the importance of the structures within that organ.
Digestion, the breakdown of foods and beverages, involves physical processes and chemical processes. The chewing action by the mouth, the peristaltic or wave-like contractions of the muscles in the esophagus and the churning and mixing action by the stomach muscles physically break large food particles into smaller ones. The saliva glands in the mouth and the cells lining the stomach, the liver and the pancreas produce enzymes that break down the small food particles further into molecules small enough for the cells lining the small intestine to absorb.
The small intestine, the longest section of the digestive system, measures approximately 6 meters long or about three times the length of your body. The pancreas and the liver secrete digestive enzymes into the small intestine to complete the chemical breakdown of food particles into small nutrient molecules. The small intestine is vital to your health because it serves as the place of absorption for nearly all the nutrients that your body needs including amino acids that are necessary to build proteins, glucose for energy, vitamins, minerals and water, according to Colorado State University.
Small Intestine Sections
The small intestine consists of three different sections that are important in the digestion of nutrients. As the digested material known as chyme passes from the stomach into the small intestine, it enters into the duodenum. Here the enzymes produced in the pancreas and bile produced by the liver mix with the chyme to complete the breakdown of proteins and carbohydrates and break apart fats. Although the duodenum absorbs some nutrients, like iron, the second section of the small intestine, the jejunum, is responsible for absorbing the majority of the nutrients. The final section, the ileum, absorbs any remaining nutrients before the material leaves the small intestine and enters the large intestine.
For absorption to occur, the nutrient must come into contact with the epithelial cells lining the small intestine. If the lining of the small intestine were just flat, many nutrients would flow right through to the large intestine and get excreted. The surface of the small intestine is not flat, however, but consists of circular folds known as mucosal folds. In addition, tiny finger-like projections known as villi line the walls of the small intestine. Microvilli, hair-like membranous projections, cover the villi. These features increase the surface area of the small intestine from approximately 1/2 square meter to 250 square meters, which greatly increases the amount of nutrients you can absorb.
- National Digestive Diseases Information Clearinghouse: Your Digestive System and How it Works
- Colorado State University: The Small Intestine
- Colorado State University: Gross and Microscopic Anatomy of the Small Intestine
- The Cleveland Clinic: The Structure and Function of the Digestive System
- Short Bowel Syndrome Foundation: Digestive Anatomy
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