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Chapter 15 The Digestive System
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 DIGESTIVE SYSTEM (FIGURE 15-1) Irregular tube called alimentary canal or gastrointestinal (GI) tract Food must first be digested, then absorbed, and later metabolized
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 3
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 4 WALL OF THE DIGESTIVE TRACT (FIGURE 15-2) Digestive tract described as tube that extends from mouth to anus Wall of the digestive tube is formed by four layers of tissue: Mucosa—mucous epithelium Submucosa—connective tissue Muscularis—two layers of smooth muscle Serosa—serous membrane that covers the outside of abdominal organs; it attaches the digestive tract to the wall of the abdominopelvic cavity by forming folds called mesenteries
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 5
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 6 MOUTH Roof—formed by hard palate (parts of maxillary and palatine bones) and soft palate, an arch-shaped muscle separating mouth from pharynx; uvula, a downward projection of soft palate (Figure 15-4) Floor—formed by tongue and its muscles; papillae, small elevations on mucosa of tongue; taste buds, found in many papillae; lingual frenulum, fold of mucous membrane that helps anchor tongue to floor of mouth (Figure 15-4) Typical tooth (Figure 15-5) Three main parts—crown, neck, and root Enamel, which covers the crown, is hardest tissue in body
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 7
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 8
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 9
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 10 MOUTH Types of teeth—incisors, cuspids, bicuspids, and tricuspids Twenty teeth in temporary set; average age for cutting first tooth about 6 months; set complete at about 2 years of age Thirty-two teeth in permanent set; 6 years about average age for starting to cut first permanent tooth; set complete usually between ages of 17 and 24 years (Figure 15-6)
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 11 SALIVARY GLANDS (FIGURE 15-7) Parotid glands—largest salivary glands Submandibular glands—open into mouth on either side of frenulum Sublingual glands—open into floor of mouth
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 12
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 13 PHARYNX Subdivided into three anatomical components: Nasopharynx Oropharynx Laryngopharynx
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 14 ESOPHAGUS Connects pharynx to stomach Dynamic passageway for food
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 15 STOMACH (Figure 15-8) Size—expands after large meal; about size of large sausage when empty Food enters stomach through gastroesophageal (cardiac) sphincter Pyloric sphincter muscle closes opening between pylorus (lower part of stomach) and duodenum Wall—many smooth muscle fibers; contractions produce churning movements (peristalsis) Lining—mucous membrane; many microscopic glands that secrete gastric juice and hydrochloric acid into stomach; mucous membrane lies in folds (rugae) when stomach is empty
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 16
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 17 SMALL INTESTINE (FIGURE 15-9) Size—about 7 meters (20 feet) long but only 2 cm or so in diameter Divisions Duodenum Jejunum Ileum
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 18
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 19 SMALL INTESTINE Wall—contains smooth muscle fibers that contract to produce peristalsis Lining—mucous membrane; many microscopic glands (intestinal glands) secrete intestinal juice; villi (microscopic finger-shaped projections from surface of mucosa into intestinal cavity) contain blood and lymph capillaries
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 20 LIVER AND GALLBLADDER Size and location—liver is largest gland; fills upper right section of abdominal cavity and extends over into left side Liver secretes bile Ducts (Figure 15-10) Hepatic—drains bile from liver Cystic—duct by which bile enters and leaves gallbladder Common bile—formed by union of hepatic and cystic ducts; drains bile from hepatic or cystic ducts into duodenum Gallbladder Location—undersurface of the liver Function—concentrates and stores bile produced in the liver
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 21
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 22 PANCREAS Exocrine gland that lies behind stomach Functions Pancreatic cells secrete pancreatic juice (most important digestive juice) into pancreatic ducts; main duct empties into duodenum Pancreatic islets (of Langerhans)—cells not connected with pancreatic ducts; secrete hormones glucagon and insulin into the blood
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 23 LARGE INTESTINE (FIGURE 15-12) Divisions Cecum Colon—ascending, transverse, descending, and sigmoid Rectum Food enters through ileocecal valve; external opening called anus Wall—contains smooth muscle fibers that contract to produce churning, peristalsis, and defecation Lining—mucous membrane
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Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 24
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