Villi

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vil·lus / ˈviləs/ (pl. vil·li / ˈvilī; ˈvilē/ ) • n. 1. Anat. any of numerous minute elongated projections set closely together on a surface, typically increasing its surface area for the absorption of substances, in particular: ∎  a fingerlike projection of the lining of the small intestine. ∎  a fold of the chorion. 2. [(usu. in pl. )] Bot. a long slender hair.

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villus (pl. villi) A small outgrowth from the surface of certain tissues that serves to increase the surface area. In mammals, villi occur in large numbers in the duodenum (where they are finger-like) and ileum (where they are paddle-like); they are covered in absorptive epithelium, each with a lymph vessel, are supplied with blood vessels, move constantly, and absorb nutrients in solution. In mammals, villi also occur on the surface of the chorion in the placenta where they increase the area available for the transfer of materials between the maternal and foetal blood.

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villus (pl. villi) A microscopic outgrowth from the surface of some tissues and organs, which serves to increase the surface area of the organ. Numerous villi line the interior of the small intestine. Their shape may vary from finger-like (in the duodenum) to spadelike (in the ileum). Intestinal villi are specialized for the absorption of soluble food material: each contains blood vessels and a lymph vessel (see lacteal).

Chorionic villi occur on the chorion of the mammalian placenta, where they increase the surface area for the exchange of materials between the fetal and maternal blood.

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villi In anatomy, small, finger-like projections of a mucous membrane such as that which lines the inner walls of the small intestine. They increase the absorptive surface area of the gut. In digestion, intestinal villi absorb most of the products of food broken down in the stomach, duodenum, and ileum.

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villus (vil-ŭs) n. (pl. villi) one of many short finger-like processes that project from the surfaces of some membranes. arachnoid v. see arachnoid. chorionic v. any of the folds of the chorion from which the fetal part of the placenta is formed. They provide an extensive area for the exchange of oxygen, nutrients, etc., between maternal and fetal blood. intestinal v. any of numerous projections that line the small intestine. Each contains a network of blood capillaries and a lacteal. Their function is to absorb the products of digestion and they greatly increase the surface area over which this can take place.

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villi: see digestive system.