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Intestinal villi (sg.: villus) are small, finger-like projections that extend into the lumen of the small intestine. Each villus is approximately 0.5–1.6 mm in length (in humans), and has many microvilli projecting from the enterocytes of its epithelium which collectively form the striated or brush border .
A glycocalyx surface coat contains digestive enzymes. Microvilli on the apical surface increase its surface area. This facilitates transport of numerous small molecules into the enterocyte from the intestinal lumen. These include broken down proteins, fats, and sugars, as well as water, electrolytes, vitamins, and bile salts.
The destruction of microvilli can actually be beneficial sometimes, as in the case of elimination of microvilli on white blood cells which can be used to combat auto immune diseases. [6] Congenital lack of microvilli in the intestinal tract causes microvillus atrophy, a rare, usually fatal condition found in new-born babies.
The circular folds slow the passage of the partly digested food along the intestines, and afford an increased surface for absorption. [4] They are covered with small finger-like projections called villi (singular, villus). Each villus, in turn, is covered with microvilli. The microvilli absorb fats and nutrients from the chyme.
The digestive tract continues as the jejunum which continues as the ileum. The jejunum, the midsection of the small intestine contains circular folds, flaps of doubled mucosal membrane which partially encircle and sometimes completely encircle the lumen of the intestine. These folds together with villi serve to increase the surface area of the ...
Intestinal glands are found in the epithelia of the small intestine, namely the duodenum, jejunum, and ileum, and in the large intestine (colon), where they are sometimes called colonic crypts. Intestinal glands of the small intestine contain a base of replicating stem cells , Paneth cells of the innate immune system , and goblet cells , which ...
Microvilli are present on the epithelium of a villus and further increase the surface area over which absorption can take place. Numerous intestinal glands as pocket-like invaginations are present in the underlying tissue.
Gastrointestinal physiology is the branch of human physiology that addresses the physical function of the gastrointestinal (GI) tract.The function of the GI tract is to process ingested food by mechanical and chemical means, extract nutrients and excrete waste products.