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Welcome to Unit 5 Chapters 15 & 16 Chapter 15 The Digestive System DIGESTIVE SYSTEM (FIGURE 15-1) Irregular tube called alimentary canal or gastrointestinal (GI) tract Food must first be digested, then absorbed, and later metabolized Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 3 2 6 7 8 1 3 4 55 9 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 4 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 5 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 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 6 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 7 1 2 3 4 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 8 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 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 9 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 10 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 11 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) Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 12 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 13 What is the largest salivary gland? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 14 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 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 15 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 16 PHARYNX Tubelike structure that allows both food and air to pass. Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 17 What connects the pharynx to the stomach? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 18 ESOPHAGUS Connects pharynx to stomach Dynamic passageway for food Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 19 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 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 20 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 21 SMALL INTESTINE (FIGURE 15-9) Size—about 7 meters (20 feet) long but only 2 cm or so in diameter What are the three divisions Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 22 SMALL INTESTINE (FIGURE 15-9) Divisions Duodenum Jejunum Ileum Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 23 The surface is folded and covered with villi. Can you tell what this does? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 24 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 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 25 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 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 26 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 27 What does bile do? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 28 Bile acts as a detergent to mechanically break up, or emulsify fats. Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 29 What is the exocrine gland that lies behind stomach? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 30 PANCREAS 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 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 31 Large Intestine What are the three divisions? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 32 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 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 33 ? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 34 APPENDIX Blind tube off cecum No important digestive functions in humans Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 35 PERITONEUM (FIGURE 15-14) Definitions—peritoneum, serous membrane lining abdominal cavity and covering abdominal organs; parietal layer of peritoneum lines abdominal cavity; visceral layer of peritoneum covers abdominal organs; peritoneal space lies between parietal and visceral layers Extensions—largest are the mesentery and greater omentum Mesentery is extension of parietal peritoneum, which attaches most of small intestine to posterior abdominal wall Greater omentum, or “lace apron,” hangs down from lower edge of stomach and transverse colon over intestines X-ray studies of the GI tract—radiopaque contrast medium used to help visualize structures in study images Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 36 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 37 DIGESTION (TABLE 15-2) Definition—transforms foods into substances that can be absorbed and used by cells Mechanical digestion—chewing (mastication), swallowing (deglutition), and peristalsis break food into tiny particles, mix them well with digestive juices, and move them along the digestive tract Chemical digestion—breaks up large food molecules into compounds that have smaller molecules; brought about by digestive enzymes (Figure 15-15) Enzymes and chemical digestion Enzymes are specialized protein molecules that act as catalysts Breakdown process called hydrolysis Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 38 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 39 DIGESTION Carbohydrate digestion—mainly in small intestine Pancreatic amylase—breaks polysaccharides down to disaccharides Intestinal juice enzymes • Maltase—changes maltose to glucose • Sucrase—changes sucrose to glucose • Lactase—changes lactose to glucose Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 40 DIGESTION Protein digestion—starts in stomach; completed in small intestine Gastric juice enzyme pepsin partially digests proteins Pancreatic enzyme, trypsin, continues digestion of proteins Intestinal enzymes, peptidases, complete digestion of partially digested proteins and convert them to amino acids Fat digestion Bile contains no enzymes but emulsifies fats (breaks fat droplets into very small droplets) Pancreatic lipase changes emulsified fats to fatty acids and glycerol in small intestine Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 41 ABSORPTION Definition—process by which digested food moves from intestine into blood or lymph Foods and most water minerals and vitamins are absorbed from small intestine; some water and vitamin K also absorbed from large intestine Surface area absorption Structural adaptations increase absorptive surface area Fractal geometry—study of fragmented geometric irregular shapes such as those in lining of intestine Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 42 Chapter 16 Nutrition and Metabolism DEFINITIONS Nutrition—food, vitamins, and minerals that are ingested and assimilated into the body Metabolism—process of using food molecules as energy sources and as building blocks for our own molecules Catabolism—breaks food molecules down, releasing their stored energy; oxygen used in catabolism Anabolism—builds food molecules into complex substances Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 44 ROLE OF THE LIVER Secretes bile, which breaks down large fat globules Helps maintain normal blood glucose level Helps metabolize carbohydrates, fats, and proteins; synthesizes several kinds of protein compounds Removes toxins from the blood Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 45 NUTRIENT METABOLISM Carbohydrates—preferred energy food of the body What are the three series of chemical reactions in glucose metabolism? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 46 NUTRIENT METABOLISM Carbohydrates—preferred energy food of the body Three series of chemical reactions in glucose metabolism • Glycolysis Changes glucose to pyruvic acid Anaerobic (uses no oxygen) Yields small amount of energy (transferred to ATP) Occurs in cytoplasm • Citric acid (Krebs) cycle Changes pyruvic acid to carbon dioxide Aerobic (requires oxygen) Yields large amount of energy (mostly as high energy electrons) Occurs in mitochondria • Electron transfer system Transfers energy from high energy electrons (from citric acid cycle) to ATP molecules Located in mitochondria Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 47 NUTRIENT METABOLISM Carbohydrates (cont.) Carbohydrates are primarily catabolized for energy (Figure 16-1), but small amounts are anabolized by glycogenesis (a series of chemical reactions that changes glucose to glycogen—occurs mainly in liver cells where glycogen is stored) Adenosine triphosphate (ATP)—molecule in which energy obtained from breakdown of foods is stored; serves as a direct source of energy for cellular work (Figure 16-2) Blood glucose (imprecisely, blood sugar)—normally stays between about 80 and 110 mg per 100 mL of blood during fasting; insulin accelerates the movement of glucose out of the blood into cells, therefore decreases blood glucose and increases glucose catabolism Fats—catabolized to yield energy and anabolized to form adipose tissue (Figure 16-3) Proteins—primarily anabolized and secondarily catabolized Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 48 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 49 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 50 Catabolism of nutrients Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 51 VITAMINS AND MINERALS Vitamins—organic molecules that are needed in small amounts for normal metabolism (Table 16-2) Minerals—inorganic molecules found naturally in the earth, required by the body for normal function (Table 16-3) Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 52 METABOLIC RATES Basal metabolic rate (BMR)—rate of metabolism when a person is lying down but awake and not digesting food and when the environment is comfortably warm Total metabolic rate (TMR)—the total amount of energy, expressed in calories, used by the body per day (Figure 16-4) Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 53 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 54 BODY TEMPERATURE Hypothalamus—regulates the homeostasis of body temperature (thermoregulation) through a variety of processes Skin—can cool the body by losing heat from the blood through four processes: radiation, conduction, convection, evaporation (Figure 16-5) Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 55 Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 56 Questions?? Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 57