Digestive absorptive unit

The food, now in a liquid form known as chyme, passes through the pyloric sphincter into the duodenum, where stomach acid is neutralized. There is wide variation in lengths of the components of the small intestine (i.e., duodenum, jejunum, and ileum) between individuals (Table 98-1). Most absorption of digested carbohydrate and protein occurs within the jejunum. Most fat absorption occurs within the jejunum and ileum. In the small bowel, breakdown of macronutrients (i.e., carbohydrate, protein, and fat) occurs both within the lumen of the gut and at the intestinal mucosal membrane surface. The absorptive units on the intestinal mucosal membrane are infoldings known as... 

Mn(II) and Fe(II) were determined by differential pulse voltammetry (9, 30). The determinations were carried out within a few hours after sampling. Total dissolved and particulate Fe and Mn (after digestion of the particulate matter in a microwave digestion unit with HN03-HC1) were measured by flame or graphite furnace atomic absorption spectrometry. 

Drug formulations Impaired digestion in cystic fibrosis affects about 90% of patients. As soon as pancreatic insufficiency is identified, enzyme supplementation is prescribed, even for breast fed infants. In a prospective, randomized study 40 infants and toddlers were treated with Creon for children, a formulation that contains smaller granules and is administered with a dosing spoon (5000 lipase units per scoop) and Creon 10 000 for 2 weeks each in a crossover design [113 ]. The former was superior in terms of parents preference, but equally effective with regard to fat absorption. Three patients who took Creon for children had treatment-related adverse events abdominal pain, constipation, vomiting, with one withdrawal) compared with one who took Creon 10 000 (severe diaper dermatitis/nappy rash). 

CHEMICAL DIGESTION AND ABSORPTION OF NUTRIENTS. Chemical digestion is the process whereby proteins, fats, and complex carbohydrates are broken down into units that are of small enough size to be absorbed from the digestive tract Into the circulation and distributed to the cells of the body. 

The efficiency of absorption of -carotene is considerably lower (9-22%) and more variable than that of retinol. In fact, in controlled studies some subjects have absorbed little, if any, of a test dose of -carotene. In individuals who do absorb dietary carotenoids, the efficiency of absorption tends to fall as intake increases. The type of carotenoid and its physical form in the ingested foodstuff also affect the efficiency of carotene absorption. Pure /3-carotene in an oily solution or supplements is absorbed more efficiently than an equivalent amount of /3-carotene in foods. Much of the carotenoid present in foods is boimd within a matrix of polysaccharides, fibers, and phenoHc compounds that is incompletely digested. Although the absorption of provitamin A carotenoids from fruits is generally better than from fibrous vegetables, it is still low as compared to yS-carotene in oil (see section on Units). 

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