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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. Each of these microvilli are about 1 ...
The small intestine tract: This is where absorption takes place. [2] [3] [4] The brush borders of the intestinal lining are the site of terminal carbohydrate digestions. The microvilli that constitute the brush border have enzymes for this final part of digestion anchored into their apical plasma membrane as integral membrane proteins.
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 barrier formed by the intestinal epithelium separates the external environment (the contents of the intestinal lumen) from the body [15] and is the most extensive and important mucosal surface of body. [18] The intestinal epithelium serves several crucial functions, exhibiting both innate and adaptive immune features.
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 ...
lubricate the intestinal walls. However, more recent studies have demonstrated that Brunner’s glands actually act as major modulators of the gut microbiome and systemic immunity. They are the distinguishing feature of the duodenum, and are named for the Swiss physician who first described them, Johann Conrad Brunner .
Epithelium/intestinal glands: Digestion and absorption of nutrients in chyme Goblet cell: Epithelium/intestinal glands: Secretion of mucus Paneth cell: Intestinal glands: Secretion of the bactericidal enzyme lysozyme; phagocytosis G cells: Intestinal glands of duodenum: Secretion of the hormone intestinal gastrin: I cells: Intestinal glands of ...