{"id":342,"date":"2021-12-11T20:34:46","date_gmt":"2021-12-12T01:34:46","guid":{"rendered":"https:\/\/opentextbc.ca\/nursingpharmacology\/chapter\/7-2-gastrointestinalconcepts\/"},"modified":"2023-08-15T14:18:09","modified_gmt":"2023-08-15T18:18:09","slug":"7-2-gastrointestinalconcepts","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/nursingpharmacology\/chapter\/7-2-gastrointestinalconcepts\/","title":{"raw":"7.2 Gastrointestinal Elimination Concepts","rendered":"7.2 Gastrointestinal Elimination Concepts"},"content":{"raw":"

Concepts Related to Gastrointestinal Elimination<\/h1>\r\nThis resource provides a basic introduction to the concept of gastrointestinal elimination as it relates to pharmacology. The concept of gastro-intestinal elimination is defined as \"the excretion of waste products\"[footnote] Jean Giddens, Concepts of Nursing Practice \u2013 2nd edition<\/em> (Missouri: Elsevier, 2017), page 138[\/footnote] specifically through the gastrointestinal system. This chapter also discusses nausea and vomiting, which are also connected to the gastrointestinal system.\r\n\r\nThe example concept map below in figure 7.2a provides a summary of the key information necessary to understand gastrointestinal elimination informed by several resources.[footnote] Jean Giddens, Concepts of Nursing Practice \u2013 2nd edition<\/em> (Missouri: Elsevier, 2017)[\/footnote]\r\n\r\nYou are encouraged to revisit this map after you have completed the chapter.<\/a>\r\n\r\n[caption id=\"attachment_341\" align=\"aligncenter\" width=\"1059\"]\"concept Figure 7.2a GI Elimination Concept Map [Image Description<\/a>][\/caption]\r\n

Overview of Gastrointestinal System and Processes<\/h1>\r\nIt is important to understand GI anatomy and physiology information in order to understand how GI medications work. Figure 7.2b[footnote]\"Components of the Digestive System\" <\/a>by CNX OpenStax<\/a> is licensed under CC BY 4.0<\/a> Access for free at https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/23-1-overview-of-the-digestive-system<\/a>[\/footnote] illustrates the anatomical components of the gastrointestinal system as a whole. The remainder of this section will provide a review of the digestive system, digestive system processes and regulation, the stomach, the small and large intestines, and chemical digestion and absorption. Medications related to hyperacidity, bowel disorders, and nausea and vomiting will be discussed later in the chapter, with reference to how they target pathophysiological concepts related to these organs and processes.\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"570\"]\"Illustrations Figure 7.2b Components of GI System[\/caption]\r\n\r\nWatch the videos below for a review of the gastrointestinal system and digestive system.\r\n
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Gastrointestinal System Review[footnote]Forciea, B. ( 2015, March 18). Anatomy and Physiology of the Digestive System<\/em> [Video]. YouTube. All rights reserved. Video used with permission. https:\/\/youtu.be\/1ssJV-EpfiQ<\/a>.[\/footnote]<\/h1>\r\n[embed]https:\/\/www.youtube.com\/watch?v=1ssJV-EpfiQ[\/embed]\r\n\r\n<\/div>\r\n
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Ted Ed Review of The Digestive System[footnote]Bryce, E. (2017, December 14). How Your Digestive System Works.<\/em> [YouTube].\u00a0 https:\/\/youtu.be\/Og5xAdC8EUI<\/a>. [\/footnote]<\/h1>\r\n[embed]https:\/\/www.youtube.com\/watch?v=Og5xAdC8EUI[\/embed]\r\n

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Khan Academy Review of GI system<\/a>[footnote]Meet the Gastrointestinal Tract!<\/a> by Raja Narayan is licensed under CC BY-NC-SA 3.0<\/a>[\/footnote]<\/h1>\r\nhttps:\/\/youtu.be\/Oh_Pt_UrtEE\r\n\r\n<\/div>\r\n

The Stomach and Digestion<\/h2>\r\nThe stomach contains cells that secrete different substances as part of the digestive process: parietal cells, chief cells, and surface epithelium cells. See an image of the stomach and these cells in Figure 7.2c.[footnote]\"2415 Histology of StomachN.jpg<\/a>\" by CNX OpenStax<\/a> is licensed under CC BY 3.0<\/a> Access for free at https:\/\/cnx.org\/contents\/FPtK1zmh@16.7:O9dvCxUQ@8\/23-4-The-Stomach<\/a>[\/footnote]\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1214\"]\"Illustration Figure 7.2c An image of the stomach with surface epithelium cells in the mucosa, and an enlarged image of the gastric gland showing chief cells and parietal cells[\/caption]\r\n\r\n[pb_glossary id=\"642\"]Surface epithelium cells[\/pb_glossary]<\/strong> are found within the lining of the stomach and secrete mucus as a protective coating. Parietal cells and chief cells are found within the gastric glands. [pb_glossary id=\"643\"]Parietal cells[\/pb_glossary]<\/strong> produce and secrete hydrochloric acid (HCl) to maintain the acidity of the environment of a pH of 1 to 4. Parietal cells also secrete a substance called [pb_glossary id=\"730\"]intrinsic factor[\/pb_glossary]<\/strong>, which is necessary for the absorption of vitamin B12 in the small intestine. Parietal cells are the primary site of action for many drugs that treat acid-related disorders. Chief cells secrete pepsinogen that becomes [pb_glossary id=\"645\"]pepsin[\/pb_glossary]<\/strong>, a digestive enzyme, when exposed to acid. The stomach also contains enteroendocrine cells (ECL or enterochromaffin-like cells) located in the gastric glands that secrete substances including serotonin, histamine, and somatostatin. G cells in the stomach secrete gastrin that promotes secretions of digestive substances. Although these cells play an important role in the digestive system, acid-related diseases can occur when there is an imbalance of secretions.\r\n

Elimination and Defecation<\/h3>\r\nThe digestive system is continually at work, but unless something goes amiss, you don't notice your digestive system working. The final step of digestion is called [pb_glossary id=\"652\"]defecation[\/pb_glossary]<\/strong>, when undigested materials are removed from the body as feces. During this final step, the large intestine absorbs water and changes the waste from a liquid into stool; then peristalsis helps move the stool into the rectum. Diarrhea and constipation occur when conditions occur that affect this final step of defection.\r\n\r\nThe process of defecation begins when mass movements force feces from the colon into the rectum, stretching the rectal wall and provoking the defecation reflex, which eliminates feces from the rectum. This parasympathetic reflex is mediated by the spinal cord. It contracts the sigmoid colon and rectum, relaxes the internal anal sphincter, and initially contracts the external anal sphincter. Figure 7.2d[footnote]\"Anorectum.gif<\/a>\" by U.S. Government National Institutes of Health is licensed under CC0<\/a>[\/footnote] reviews the anatomy of the rectum and its external and internal sphincters. The presence of feces in the anal canal sends a signal to the brain, which gives the person the choice of voluntarily opening the external anal sphincter (defecating) or keeping it temporarily closed. If defecation is delayed until a more convenient time, it takes a few seconds for the reflex contractions to stop and the rectal walls to relax. The next mass movement will trigger additional defecation reflexes until defecation occurs.[footnote]This work is a derivative of Anatomy and Physiology<\/a> by OpenStax<\/a> licensed under CC BY 4.0<\/a>. Access for free at https:\/\/openstax.org\/books\/anatomy-and-physiology\/pages\/1-introduction<\/a>[\/footnote]\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"297\"]\"The Figure 7.2d Anatomy of the Rectum[\/caption]\r\n\r\nIf defecation is delayed for an extended time, additional water is absorbed, making the feces firmer and potentially leading to constipation. Alternatively, if the waste matter moves too quickly through the intestines, not enough water is absorbed and diarrhea can result. Figure 7.2e[footnote]\"BristolStoolChart.png<\/a>\" by Cabot Health, Bristol Stool Chart is licensed under CC BY-SA 3.0<\/a>[\/footnote] demonstrates the Bristol Stool Chart that is used to assess stool characteristics ranging from very constipated to diarrhea.<\/a>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"961\"]\"Image Figure 7.2e Bristol Stool Chart [Image Description<\/em><\/a>][\/caption]You can further review how the digestive system works at the following links:\r\n