Absorption of nutrients

The lower rates of nutrient absorption associated with diets high in nonstarch polysaccharides are probably due to the increased viscosity of digesta (Vaugelade et al., 2000), which increases the thickness of the unstirred layer overlying the enterocytes and causes anon-specific decline in solute absorption. This explains why diets high in 3-glucans, which are structural carbohydrates and which increase viscosity of digesta, reduce absorption of nutrients and... 

Failure to thrive Below-average growth due to a medical condition. A pronounced lack of growth in a child because of inadequate absorption of nutrients or a serious heart or kidney condition, resulting in below-average height and weight. 

JR Pappenheimer, KZ Reiss. Contribution of solvent drag through intracellular junctions to absorption of nutrients by the small intestine of the rat. J Membrane Biol 100 123-136, 1987. 

Water and electrolytes. Each day in an average adult, about 5.51 of food and fluids move from the stomach to the small intestine as chyme. An additional 3.5 1 of pancreatic and intestinal secretions produce a total of 9 1 of material in the lumen. Most of this (>7.5 1) is absorbed from the small intestine. The absorption of nutrient molecules, which takes place primarily in the duodenum and jejunum, creates an osmotic gradient for the passive absorption of water. Sodium may be absorbed passively or actively. Passive absorption occurs when the electrochemical gradient favors the movement of Na+ between the absorptive cells through "leaky" tight junctions. Sodium is actively absorbed by way of transporters in the absorptive cell membrane. One type of transporter carries a Na+ ion and a Cl ion into the cell. Another carries a Na+ ion, a K+ ion, and two Cl ions into the cell. 

With such a large surface area available for the absorption of nutrients, there is the potential for the absorption of dietary constituents that could be harmful to the health of an individual. Thus, in order to protect against dietary toxins, there are a series of barriers, which must be overcome before a molecule can enter the systemic circulation. This applies equally to drug molecules. 

Sastry, K.V., D.R. Rao, and S.K. Singh. 1982. Mercury induced alterations in the intestinal absorption of nutrients in the fresh water murrel, Channa punctatus. Chemosphere 11 613-619. 

Undernutrition is the result of inadequate nutrition intake, impaired absorption of nutrients, or inappropriate use of ingested nutrients. Changes in subcellular, cellular, and/or organ function can occur and increase the risk of morbidity and mortality. 

Evenepoel, P. (2001). Alteration in digestion and absorption of nutrients during profound acid suppression. Best Pract. Res. Clin. Gastroenterol. 15, 539-551. 

A high rate of ethanol consumption can lead to inhibition of gastric secretion and irritation of the gastric mucosa. Ethanol irritates the entire gastrointestinal tract, which may lead to constipation and diminished absorption of nutrients. Other pathological effects include pancreatitis and peripheral neuropathy. Severe gonadal failure is often found in both men and women, accompanied by low blood levels of sex hormones. 

N.A. Cineole, thujone, ascorbic acid, thiamine, inulin, resin, tannin.100-102 Improve appetite, digestive function, and absorption of nutrients. Antiseptic, a uterine stimulant. 

In ruminants, avoparcin has a dual action. It acts in the rumen by enhancing fermentation, and in the intestine by improving the absorption of nutrients. Following feeding to animals, avoparcin is virtually unabsorbed from the gastrointestinal tract and is rapidly eliminated in the form of the parent compound. As a result, no withdrawal period is required. 

A resurgence of interest in dietary fiber has been stimulated by epidemiological evidence of differences in colonic disease patterns between cultures with diets containing large quantities of fiber, and Western cultures having more highly refined diets. Many African countries, for example, are relatively free of diverticular disease, ulcerative colitis, hemorrhoids, polyps, and cancer of the colon Whereas most interest has focused on the beneficial role of dietary fiber, there is also concern that high fiber diets may cause disturbances in the absorption of nutrients such as minerals (see Mineral Nutrients) and vitamins. 

The plasma membrane is a delicate, semipermeable, sheetlike covering for the entire cell. Forming an enclosure prevents gross loss of the intracellular contents the semipermeable character of the membrane permits the selective absorption of nutrients and the selective removal of metabolic waste products. In many plant and bacterial (but not animal) cells, a cell wall encompasses the plasma membrane. The cell wall is a more porous structure than the plasma membrane, but it is mechanically stronger because it is constructed of a covalently cross-linked, three-dimensional network. The cell wall maintains a cell s three-dimensional form when it is under stress. 

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