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High-Yield Terms
Serous fluid: a watery pale yellow transparent fluid enriched in proteins and water produced by cells of serous glands
Mucus: a viscous mixture covering mucus membranes, produced and secreted by cells of mucus membranes, consists of glycoproteins termed mucins, water, and several other proteins such as antiseptic enzymes and immunoglobulins
Chyme: represents the semifluid mass of partially digested food expelled by the stomach into the duodenum
Enterocytes: columnar epithelial cells of the intestines responsible for nutrient uptake
Goblet cell: glandular epithelial cells that secrete the glycoproteins termed mucins
Chief cell: gastric chief cells are those cells in the stomach that secrete the zymogen and pepsinogen; the parathyroid gland also contains chief cells
Parietal cell: stomach glandular epithelial cells that secrete gastric acid in response to histamine, acetylcholine, and gastrin stimulation
Oxyntic cell: another name for parietal cells
Duct cell: specialized cells lining the pancreatic ducts that secrete bicarbonate
Acinar cell: a cell of an acinus which is any cluster of cells that resembles a many-lobed berry-like structure that is the terminus of an exocrine gland; acinar cells of pancreas are the duct cells that secrete bicarbonate and digestive enzymes
Enteroendocrine cell: specialized endocrine cells found in the intestines and pancreas that produce various gastrointestinal hormones and bioactive peptides
Enterochromaffin-like cell (ECL): neuroendocrine cells that secrete histamine and are found in gastric glands of the gastric mucosa
Gut microbiota: refers to the complex mixture of microorganisms (bacteria, fungi, viruses) that reside within the gastrointestinal tract
Prebiotic: refers to any nondigestible substance in food that stimulates the growth and/or activity of intestinal system bacteria
Probiotic: refers to live bacteria that can be consumed in order to confer a health benefit
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Overview of Digestive System
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The gastrointestinal (GI) system, with respect to the processes of food ingestion and digestion, comprises the hollow organs that include the oral cavity, the esophagus, the stomach, and the small and large intestines (Table 43-1). In addition to these hollow organs, ingestion and digestion of food requires several accessory glands and other organs that add secretions to the hollow organs of the GI. The primary accessory organs necessary for digestion are the salivary glands present within the oral cavity, the pancreas, and the liver.
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The GI organs are separated from each other at key locations by specialized structures termed sphincters. Entry of food from the oral cavity to the esophagus requires passage ...