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Biology Sylvia S. Mader Michael Windelspecht
Chapter 34 Digestive Systems and Nutrition Lecture Outline See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1
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Biology, 9th ed, Sylvia Mader
Chapter 36 Outline Digestive Systems and Nutrition 34.1 Digestive Tracts 34.2 The Human Digestive System 34.3 Digestive Enzymes 34.4 Nutrition and Human Health
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Biology, 9th ed, Sylvia Mader
Chapter 36 34.1 Digestive Tracts Digestive Systems and Nutrition Digestive System Included all the organs, tissues, and cells involved in ingesting food and breaking it down into smaller components. A digestive system: Ingests food Breaks food down into small molecules that can cross plasma membranes Absorbs nutrient molecules Eliminates undigestible remains
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Biology, 9th ed, Sylvia Mader
Chapter 36 Digestive Tracts Digestive Systems and Nutrition Incomplete versus Complete Tracts An incomplete digestive tract has a single opening Example: Planarian Food enters through mouth and muscular pharynx Gastrovascular cavity branches throughout the body Wastes exit through mouth and muscular pharynx Lacks specialized parts A complete digestive tract has two openings Example: Earthworm Food enters through mouth Wastes exit through anus Specialization of parts is obvious
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Incomplete Digestive Tract of a Planarian
Biology, 9th ed, Sylvia Mader Chapter 36 Incomplete Digestive Tract of a Planarian Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. mouth digestive tract pharynx Golgi apparatus lysosome gastrovascular cavity a. b.
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Complete Digestive Tract of an Earthworm
Biology, 9th ed, Sylvia Mader Chapter 36 Complete Digestive Tract of an Earthworm Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. typhlosole anus mouth pharynx intestine esophagus crop gizzard
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Biology, 9th ed, Sylvia Mader
Chapter 36 Digestive Tracts Digestive Systems and Nutrition Continuous vs. Discontinuous Feeders Continuous filter feeders Example: Clams Always have water moving into the mantle cavity via the incurrent siphon Particles are deposited on gills Do not need food storage area Discontinuous feeders Example: Squid Uses tentacles to seize prey Beaklike jaws pull pieces into the mouth with the radula Food storage area needed
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Nutritional Mode of a Clam Compared to a Squid
Biology, 9th ed, Sylvia Mader Chapter 36 Nutritional Mode of a Clam Compared to a Squid Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. arm tentacle stomach kidney digestive gland jaw radula rectum pharynx water flow esophagus anus digestive gland anus intestine stomach gills water flow kidney excurrent siphon mouth cecum incurrent siphon mantle gonad labial palps gills pen muscular foot gonad intestine mantle a. Digestive system (green) of clam b. Digestive system (green) of squid
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Biology, 9th ed, Sylvia Mader
Chapter 36 Digestive Tracts Digestive Systems and Nutrition Adaptation to Diet Dentition differs with mode of nutrition Omnivores Variety of specializations to accommodate both vegetation and meat Herbivores Incisors for clipping Premolars and molars for grinding Carnivores Pointed incisors and enlarged canines Shear off pieces small enough to swallow
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Dentition Among Mammals
Biology, 9th ed, Sylvia Mader Dentition Among Mammals Chapter 36 Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. reduced canines large, flat molars and premolars sharp incisors a. Horses are herbivores. chisel-shaped incisors pointed canines pointed incisors fairly flat premolars Lion flat molars enlarged canines jagged molars and premolars c. Humans are omnivores. similarly shaped conical teeth Dolphin b. Lions and dolphins are carnivores.
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34.2 The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 34.2 The Human Digestive System Digestive Systems and Nutrition Human digestive tract is complete Part of a tube-within-a-tube body plan Begins with a mouth and ends in an anus Digestion is entirely extracellular Digestive enzymes are secreted by The wall of the digestive tract nearby accessory glands
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The Human Digestive Tract
Biology, 9th ed, Sylvia Mader The Human Digestive Tract Chapter 36 Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Accessory organs Digestive tract organs Mouth teeth chew food; tongue tastes and pushes food for chewing and swallowing Salivary glands secrete saliva: contains digestive enzyme for carbohydrates Pharynx passageway where food is swallowed Esophagus passageway where peristalsis pushes food to stomach Liver major metabolic organ: processes and stores nutrients; produces bile for emulsification of fats Stomach secretes acid and digestive enzyme for protein; churns, mixing food with secretions, and sends chyme to small intestine Gallbladder stores bile from liver; sends it to the small intestine Small intestine mixes chyme with digestive enzymes for final breakdown; absorbs nutrient molecules into body; secretes digestive hormones into blood Pancreas produces pancreatic juice: contains digestive enzymes, and sends it to the small intestine; produces insulin and secretes it into the blood after eating Large intestine absorbs water and salt to form feces Rectum stores and regulates elimination of feces Anus
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Mouth Three major pairs of salivary glands Saliva contains salivary amylase initiates starch digestion Tongue is composed of striated muscle Mixes chewed food with saliva Forms mixture into a bolus
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition The Pharynx and Esophagus Pharynx Digestive and respiratory passages come together in the pharynx, then separate Soft palate closes off nasopharynx during swallowing Epiglottis Covers the glottis (opening into the trachea) Keeps food from air passages (most of the time) Esophagus Moves food to stomach by peristalsis Peristalsis - Rhythmical contraction to move contents in tubular organs
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Biology, 9th ed, Sylvia Mader
Chapter 36 Digestive Systems and Nutrition Swallowing Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. soft palate nasopharynx hard palate uvula bolus epiglottis covering glottis glottis trachea esophagus
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Peristalsis in the Digestive Tract
Biology, 9th ed, Sylvia Mader Chapter 36 Peristalsis in the Digestive Tract Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. esophagus bolus
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Stomach Stomach wall has deep folds Folds disappear as the stomach fills to an approximate volume of one liter Epithelial lining of the stomach has millions of gastric pits, which lead to gastric glands Gastric glands secrete hydrochloric acid and pepsin Pepsin is a hydrolytic enzyme that acts on protein to produce peptides
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Biology, 9th ed, Sylvia Mader
Anatomy of the Stomach Chapter 36 Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. esophagus muscles of the stomach wall duodenum of small intestine gastric pit a. cells that secrete mucus gastric gland cells that secrete HCl and enzymes 20 mm b. b: © Ed Reschke/Peter Arnold, Inc.
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Stomach (continued) Food mixing with gastric juices becomes chyme Junction between the stomach and the small intestine is controlled by a sphincter When the sphincter relaxes, a small quantity of chyme passes into the small intestine
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition The Small Intestine First segment is duodenum Chyme from stomach enters the duodenum Chyme mixes with secretions from the liver and pancreas Liver Produces bile, which is stored in gallbladder Bile contains bile salts which break up fat into fat droplets via emulsification
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition The Small Intestine (continued) Pancreas Exocrine gland Secretes pancreatic juice and digestive enzymes into the duodenum Epithelial cells of the small intestine also produce digestive enzymes These enzymes complete the process of food digestion in the small intestine
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Wall of the small intestine Villi are ridges on the surface, which contain even smaller ridges called microvilli Greatly increase the surface area for absorption Each villus contains blood capillaries and a lacteal (lymphatic capillary)
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Anatomy of the Small Intestine
Biology, 9th ed, Sylvia Mader Chapter 36 Anatomy of the Small Intestine Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Small intestine Section of intestinal wall villus lumen lacteal blood capillaries villus microvilli goblet cell lymph nodule venule lymphatic vessel ×100 Villi arteriole (Villi): © Manfred Kage/Peter Arnold, Inc.; (Microvilli): Photo by Susumu Ito, from Charles Flickinger, Medical Cellular Biology, W.B. Saunders, 1979
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Large Intestine Includes cecum, colon, rectum, and anus Larger in diameter, but shorter in length than small intestine Cecum has small projection - the appendix Absorbs water, salts, and some vitamins Stores undigestible material until it is eliminated at the anus Has a large population of bacteria that break down undigestible material and produce vitamins
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Junction of the Small Intestine and the Large Intestine
Biology, 9th ed, Sylvia Mader Chapter 36 Junction of the Small Intestine and the Large Intestine Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. large intestine small intestine cecum vermiform appendix
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Accessory Organs Pancreas Lies deep in the abdominal cavity Endocrine function Secretes insulin and glucagon to regulate blood glucose levels Exocrine function Secretes pancreatic juice and digestive enzymes Sodium bicarbonate in pancreatic juice neutralizes acid chyme from the stomach Pancreatic amylase digests starch Trypsin digests protein Lipase digests fat 26
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Accessory Organs (continued): Liver Largest gland in the body Located in the upper right abdominal cavity, under the diaphragm Lobules are its structural and functional units Triads consist of A bile duct A branch of the hepatic artery A branch of the hepatic portal vein Blood moves from the intestines to the liver via the hepatic portal vein Blood moves from the liver to the inferior vena cava via the hepatic veins 27
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Functions of the liver Detoxification of the blood Storage of iron and some vitamins Production of plasma proteins Storage of glucose as glycogen Production of urea Removal of bilirubin Regulation of blood cholesterol levels 28
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Liver Disorders Jaundice – yellowing of skin due to excess bilirubin Hepatitis – inflammation of liver, primarily caused by a virus Cirrhosis – scaring of liver tissue leading to reduced function 29
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The Human Digestive System
Biology, 9th ed, Sylvia Mader Chapter 36 The Human Digestive System Digestive Systems and Nutrition Accessory Organs (continued): Gallbladder Pear-shaped, muscular sac attached to the liver Stores excess bile Gallstones form when the cholesterol in bile crystallizes 30
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Liver, Gallbladder, and Pancreas
Biology, 9th ed, Sylvia Mader Liver, Gallbladder, and Pancreas Chapter 36 Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. bile common hepatic duct pancreas pancreatic duct pancreatic juice gallbladder common bile duct duodenum a. branch of hepatic artery bile canals central vein branch of hepatic portal vein bile duct b.
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Biology, 9th ed, Sylvia Mader
Chapter 36 34.3 Digestive Enzymes Digestive Systems and Nutrition salivary amylase starch + H2O maltose pepsin protein + H2O peptides pancreatic amylase
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Biology, 9th ed, Sylvia Mader
Chapter 36 Digestive Enzymes Digestive Systems and Nutrition trypsin protein + H2O peptides maltase maltose + H2O glucose + glucose peptidases peptides + H2O amino acids
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Digestion and Absorption of Nutrients
Biology, 9th ed, Sylvia Mader Chapter 36 Digestion and Absorption of Nutrients Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. carbohydrate protein + pancreatic amylase bile salts fat globules trypsin emulsification droplets peptides maltase epithelial cell of intestinal villus peptidase lipase glucose monoglycerides and free fatty acids amino acids pH = basic chylomicron pH = basic pH = basic lymphatic capillary blood capillary blood capillary a. Carbohydrate digestion b. Protein digestion c. Fat digestion
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34.4 Nutrition and Human Health
Biology, 9th ed, Sylvia Mader Chapter 36 34.4 Nutrition and Human Health Digestive Systems and Nutrition Carbohydrates Carbohydrates are present in food in the form of sugars, starch, and fiber. Fruits, vegetables, milk, and honey are natural sources of sugars. Monosaccharides: Glucose Fructose Disaccharides: Lactose (milk sugar) Sucrose (table sugar)
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Nutrition and Human Health
Biology, 9th ed, Sylvia Mader Chapter 36 Nutrition and Human Health Digestive Systems and Nutrition Carbohydrates: After being absorbed from the digestive tract all sugars are converted to glucose Glucose is the preferred direct energy source in cells. Plants store glucose as starch Animals store glucose as glycogen
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Nutrition and Human Health
Biology, 9th ed, Sylvia Mader Chapter 36 Nutrition and Human Health Digestive Systems and Nutrition Fiber Includes various undigestible carbohydrates derived from plants Food sources rich in fiber include beans, peas, nuts, fruits, and vegetables Technically, fiber is not a nutrient for humans Cannot be digested Soluble fiber combines with bile acids and cholesterol in the small intestine and prevents them from being absorbed
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Biology, 9th ed, Sylvia Mader
Chapter 36 Fiber Rich Food Digestive Systems and Nutrition Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Amiard/Photocuisine/Corbis
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Nutrition and Human Health
Biology, 9th ed, Sylvia Mader Chapter 36 Nutrition and Human Health Digestive Systems and Nutrition Lipids Fat, oils, and cholesterol Saturated fatty acids (solids at room temperature) usually come from animals Butter, meat, whole milk, and cheeses contain saturated fats Unsaturated fatty acids are found in plant oils Cholesterol can be synthesized by the body and is found in animal foods
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Nutrition and Human Health
Biology, 9th ed, Sylvia Mader Chapter 36 Nutrition and Human Health Digestive Systems and Nutrition Proteins Adequate protein formation requires 20 different types of amino acids 9 essential amino acids are required in the diet Some foods, such as meat, milk, and eggs, provide all 9 (complete) Vegetables supply some essential amino acids, but are usually deficient in at least one (incomplete) Vegetarians should eat a variety of plant products to obtain all the essential amino acids
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Nutrition and Human Health
Biology, 9th ed, Sylvia Mader Chapter 36 Nutrition and Human Health Digestive Systems and Nutrition Diet and Obesity Too many calories from any source contributes to body fat. Increases risk of obesity and associated illnesses Type 2 diabetes and cardiovascular disease are often seen in people who are obese.
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Exercising for Good Health
Biology, 9th ed, Sylvia Mader Exercising for Good Health Chapter 36 Digestive Systems and Nutrition
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Nutrition and Human Health
Biology, 9th ed, Sylvia Mader Chapter 36 Nutrition and Human Health Digestive Systems and Nutrition Vitamins and Minerals Vitamins Organic compounds the body is unable to produce, but are required for metabolic purposes Minerals The body needs about 20 elements for various physiological functions
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