Search Results: Digestive system

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Figure 1.Major variations in the foregut and midgut of fish. The teeth of most fish are located on the jaws or other mouthparts, but their location in the pharynx (1) of some species such as the chub allows mastication of food without the loss of fine particles through the gills. The esophagus (2) varies in length. The stomach (3) is absent in cyclostomes, such as the lamprey, and in some advanced species, such as the chub. Where present, it may be straight as in the pike, U-shaped like that of the trout, or Y-shaped with a gastric cecum, as seen in the eel. The intestine (4) tends to be relatively short with little distinction between the midgut and hindgut in most fish, but the lumen surface area and digesta retention time of the midgut are increased by a spiral valve (5) or pyloric ceca (6) in some species. (Modified from W. Harder, Anatomy of Fishes, Part II, Schweizerbart'sche Verlagsbuchhandlung, 1975)

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Figure 2.Variations in the distribution of gastric epithelium and the degree of compartmentalization in the stomach of mammals. Stomachs are not drawn to the same scale; the stomach contents of the ox are approximately 70 times the volume and 14 times the weight of human stomach contents. (After C. E. Stevens and I. D. Hume, Comparative Physiology of the Vertebrate Digestive System, 2d ed., Cambridge University Press, 1995)

From Encyclopedia article 'Digestive system'

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Figure 3.Section of the wall of the small intestine. (a) Intestinal villus and crypt (after R. A. Argenzio et al., Villous atrophy, crypt hyperplasia, cellular infiltration, and impaired glucose-Na absorption in enteric cryptosporidiosis in pigs, Gastroenterology, 98:1129–1140, 1990). (b) Electron micrograph of microvilli on the free surface of an absorbing cell from the small intestine of a rat (courtesy of M. L. Watson).

From Encyclopedia article 'Digestive system'