University of South Dakota, Vermillion, 57069, USA.
Adv Physiol Educ. 2010 Jun;34(2):44-53. doi: 10.1152/advan.00094.2009.
Nutrient digestion and absorption is necessary for the survival of living organisms and has evolved into the complex and specific task of the gastrointestinal (GI) system. While most people simply assume that their GI tract will work properly to use nutrients, provide energy, and release wastes, few nonscientists know the details about how various nutrients are digested and how the breakdown products traverse the cells lining the small intestine to reach the blood stream and to be used by the other cells of the body. There have been several recent discoveries of new transporters that likely contribute to the absorption of oligopeptides and fatty acids. In addition, details are being clarified about how transporters work and in what forms nutrients can be absorbed. The enzymes that digest basic carbohydrates, proteins, and fats have been identified in various segments of the GI tract, and details are becoming clearer about what types of bonds they hydrolyze. Usually, detailed information about the digestion of basic nutrients is presented and learned in biochemistry courses and detailed information about absorption via transepithelial transport of the breakdown products of digestion is studied in physiology courses. The goal of this Staying Current article is to combine the details of the biochemistry of digestion with the updated information about the physiology of nutrient absorption into one source for teachers of physiology. Insights are included about some of the diseases and conditions that can bring about malabsorption of food in the GI tract and their consequences.
营养物质的消化和吸收是生物生存所必需的，它已经演变成胃肠道（GI）系统的一项复杂而特定的任务。虽然大多数人认为他们的胃肠道系统会正常运作，以利用营养物质、提供能量和排出废物，但很少有非科学家了解各种营养物质是如何被消化的，以及分解产物如何穿过小肠内壁细胞进入血液，并被身体的其他细胞利用。最近有几项关于新转运蛋白的发现，这些转运蛋白可能有助于寡肽和脂肪酸的吸收。此外，关于转运蛋白如何工作以及营养物质可以以何种形式被吸收的细节也在逐渐明晰。消化基本碳水化合物、蛋白质和脂肪的酶已经在胃肠道的各个部位被识别出来，关于它们水解哪种类型的键的细节也越来越清楚。通常，关于基本营养素消化的详细信息在生物化学课程中呈现并学习，而关于通过跨上皮细胞转运消化产物的吸收的详细信息则在生理学课程中学习。这篇 Staying Current 文章的目的是将消化的生物化学细节与营养吸收的生理学最新信息结合起来，为生理学教师提供一个资源。本文还包括了一些关于一些可能导致胃肠道食物吸收不良的疾病和情况的见解，以及它们的后果。
