Copyright © 2019, Elsevier Inc. All Rights Reserved. 1Chapter 41: Structure and Function of the Digestive SystemMcCance/Huether: Pathophysiology: The Biologic Basis of Disease in Adults and Children, 8th EditionMULTIPLE CHOICE 1. In the mouth and stomach, salivary α-amylase initiates the digestion of which nutrients?a. Proteinsb. Carbohydratesc. Fatsd. FiberANS: BSalivary α-amylase is an enzyme that initiates carbohydrate digestion in the mouth and stomach. Pepsin breaks down protein-forming chains in the stomach. Thirty percent of fats are broken down by gastric lipase. Fiber is not broken down and contributes to stool volume.PTS: 1 DIF: Cognitive Level: Remembering 2. Saliva contains which immunoglobulin (Ig)?a. IgAb. IgEc. IgGd. IgMANS: ASaliva contains only IgA, which helps prevent infection.PTS: 1 DIF: Cognitive Level: Remembering 3. What effect is a result of inhibiting the parasympathetic nervous system with a drug such as atropine?a. Salivation becomes thinner.b. Salivation decreases.c. The pH of saliva changes.d. Digestive enzymes are inhibited.ANS: BThe sympathetic and parasympathetic divisions of the autonomic nervous system control salivation. Because cholinergic parasympathetic fibers stimulate the salivary glands, atropine (an anticholinergic agent) inhibits salivation and makes the mouth dry. Atropine (and similar drugs) does not cause saliva to become thinner, change the pH of saliva, or inhibit digestive enzymes.PTS: 1 DIF: Cognitive Level: Remembering 4. Food enters the stomach via which orifice or sphincter?a. Cardiacb. Upper esophagealc. Gastricd. FundalANS: AEach end of the esophagus is opened and closed by a sphincter. The upper esophageal sphincter (cricopharyngeal muscle) prevents entry of air into the esophagus during respiration. The lower esophageal sphincter (cardiac orifice) prevents regurgitation from the stomach. The lower esophageal sphincter is located near the esophageal hiatus—the opening in the diaphragm where the esophagus ends at the stomach. The gastric sphincter controls the release of food from the stomach to the small intestine and is also known as the pyloric sphincter. The fundal sphincter is not a structure in the GI system.PTS: 1 DIF: Cognitive Level: Remembering 5. Which gastric cells secrete hydrochloric acid and intrinsic factor?a. Parietalb. Chiefc. Gd. DANS: AThe parietal cells (oxyntic cells) secrete hydrochloric acid and intrinsic factor. The chief cells secrete pepsinogen. The pyloric gland mucosa in the antrum synthesizes and releases the hormone gastrin from G cells. D cells secrete somatostatin.PTS: 1 DIF: Cognitive Level: Remembering 6. Which cells in the stomach secrete histamine?a. Oxynticb. Chiefc. Dd. Enterochromaffin-likeANS: DEnterochromaffin-like cells secrete histamine. The parietal cells (oxyntic cells) within the glands secrete hydrochloric acid, intrinsic factor, and gastroferrin. The chief cells secrete pepsinogen. D cells secrete somatostatin.PTS: 1 DIF: Cognitive Level: RememberingCopyright © 2019, Elsevier Inc. All Rights Reserved. 2 7. Which gastric hormone inhibits acid and pepsinogen secretion, as well as decreases the release of gastrin?a. Motalinb. Histaminec. Somatostatind. AcetylcholineANS: CSomatostatin inhibits the secretion of acid and pepsinogen and decreases gastrin release. The hormones gastrin and motilin stimulate gastric emptying. Histamine stimulates acid secretion by activating histamine receptors (H2 receptors) on acid-secreting parietal cells. Acetylcholine stimulates pepsin secretion.PTS: 1 DIF: Cognitive Level: Remembering 8. Which enzyme breaks down protein-forming polypeptides in the stomach?a. Acetylcholineb. Pepsinc. Gastrind. SecretinANS: BPepsin, a proteolytic enzyme, breaks down protein-forming polypeptides in the stomach. Acetylcholine stimulates pepsin secretion. The hormones gastrin and motilin stimulate gastric emptying. Secretin stimulates pancreas to secrete alkaline pancreatic juice and liver to secrete bile; decreases gastrointestinal motility; inhibits gastrin and gastric acid secretion.PTS: 1 DIF: Cognitive Level: Remembering 9. Exposure to which substance protects the mucosal barrier of the stomach?a. Prostaglandinsb. Acetylcholinec. Helicobacter pylorid. Regurgitated bileANS: AProstaglandins and nitric oxide protect the mucosal barrier by stimulating the secretion of mucus and bicarbonate and by inhibiting the secretion of acid. Acetylcholine stimulates pepsin secretion. Helicobacter pylori are bacteria found in the stomach. Bile is secreted by the liver.PTS: 1 DIF: Cognitive Level: Remembering 10. The ileum and jejunum are suspended by folds of the peritoneum that contain an extensive vascular and nervous network. What are these folds called?a. Ligament of Treitzb. Mesenteryc. Auerbach foldsd. Lamina propriaANS: BThe ileum and jejunum are suspended in loose folds from the posterior abdominal wall by a peritoneal membrane called the mesentery. The mesentery facilitates intestinal motility and supports blood vessels, nerves, and lymphatics. The duodenum begins at the pylorus and ends where it joins the jejunum at a suspensory ligament called the Treitz ligament. Intrinsic reflexive activity is mediated by the myenteric plexus (Auerbach plexus) and the submucosal plexus (Meissner plexus) of the enteric nervous system. The lamina propria (a connective tissue layer of the mucous membrane) lies beneath the epithelial cells of the villi and contains lymphocytes and plasma cells, which produce immunoglobulins and macrophages.PTS: 1 DIF: Cognitive Level: Remembering 11. Where in the small intestines are lymphocytes, plasma cells, and macrophages produced?a. Brush borderb. Microvillic. Lamina propriad. Crypts of LieberkühnANS: CThe lamina propria, which is a connective tissue layer of the mucous membrane, lies beneath the epithelial cells of the villi and contains lymphocytes, plasma cells, which produce immunoglobulins and macrophages. Together the microvilli create a mucosal surface known as the brush border. The villi and microvilli greatly increase the surface area available for absorption. Between the bases of the villi are the crypts of Lieberkühn (intestinal glands), which extend to the submucosal layer. Undifferentiated cells arise from stem cells at the base of the crypt and move toward the tip of the villus, maturing to become columnar epithelial secretory cells (water, electrolytes, and enzymes) and goblet cells (mucus).PTS:
View Full Document
Unlocking...