Chapter 9 Digestive System. Copyright 2016 McGraw-Hill Education. Permission required for reproduction or display.

Chapter 9 Digestive System Copyright 2016 McGraw-Hill Education. Permission required for reproduction or display. 1

Points to ponder What are the digestive system structures and their functions? Where does carbohydrate, protein, and fat digestion and absorption occur? What are proteins, lipids, carbohydrates, minerals and vitamins needed for? What is an essential vs. a nonessential nutrient? What are the three accessory organs of digestion? What is obesity and why is it a problem? What is LDL and HDL? What are the components of a healthy diet? Name and explain 4 eating disorders. 2

9.1 Overview of Digestion What are the main steps in the digestive process? Ingestion Digestion Movement Absorption Elimination 3

9.1 Overview of Digestion An overview of the digestive system Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Accessory organs Salivary glands secrete saliva which contains digestive enzyme for carbohydrates Digestive tract organs Mouth teeth chew food; tongue tastes and pushes food for chewing and swallowing 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 Gallbladder stores bile from liver; sends it to the small intestine Pancreas produces pancreatic juice ; contains digestive enzymes, and sends it to the small intestine; produces insulin and secretes it into the blood after eating Stomach secretes acid and digestive enzyme for protein; churns, mixing food with secretions, and sends chyme to small intestine Small intestine mixes chyme with digestive enzymes for final breakdown; absorbs nutrient molecules into body; secretes digestive hormones into blood Large intestine absorbs water and salt to form feces Figure 9.1 Organs of the GI tract and accessory structures of digestion. Rectum stores and regulates elimination of feces Anus 4

9.1 Overview of Digestion What is the pathway that food follows? mouth pharynx esophagus stomach small intestine large intestine rectum anus 5

9.2 The Mouth, Pharynx, and Esophagus Anatomy of the mouth Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. hard palate soft palate uvula tonsil molars (3) premolars (2) canine (1) Figure 9.3a The functions of the different teeth. incisors (2) 6

9.2 The Mouth, Pharynx, and Esophagus Anatomy of a tooth Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. crown enamel dentin pulp gum jawbone root canal root periodontal membrane cementum Figure 9.3b A cross section of a tooth showing the crown and root. 7

9.2 The Mouth, Pharynx, and Esophagus How do we swallow food? hard palate food bolus nasopharynx Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Soft palate closes off nasopharynx. soft palate bolus peristaltic wave epiglottis a. Swallowing glottis Esophagus is closed. trachea (airway) open Larynx rises and epiglottis covers glottis. esophagus opens esophagus b. Peristalsis Lower gastroesophageal sphincter relaxes and food enters stomach. stomach What s heartburn? Figure 9.4 The process of swallowing. 8

9.3 The Stomach and Small Intestine Anatomy of the stomach Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. esophagus lower gastroesophageal sphincter pyloric sphincter muscularis layer has three layers of muscle. mucosa layer has rugae. c. Gastric pits in mucosa gastric pit SEM 3,260x a. Stomach gastric pit gastric gland cells that secrete gastric juice pyloric sphincter lower gastroesophageal sphincter b. Gastric glands c: Dr. Fred Hossler/Visuals Unlimited d. How the stomach empties Figure 9.5 The layers of the stomach. 9

9.3 The Stomach and Small Intestine Digestion & absorption of nutrients Small intestine Figure 9.6 Absorption in the small intestine. 10

9.3 The Stomach and Small Intestine How are nutrients digested and transported out of the small intestine? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. pancreatic amylase maltase cell of intestinal villus carbohydrate glucose protein trypsin peptides peptidase amino acids + bile salts fat globules lipase emulsification droplets monoglycerides and free fatty acids ph = basic ph = basic ph = basic chylomicron blood capillary blood capillary a. Carbohydrate digestion b. Protein digestion lymphatic capillary c. Fat digestion Figure 9.7 Digestion and absorption of organic nutrients. 11

9.4 The Accessory Organs and Regulation of Secretions The 3 accessory organs Pancreas Digestive enzymes Bicarbonate Insulin/glucagon Liver Filters blood (detox) Removes: Iron duodenum Stores Vit A, D, E, K & B 12 Bile Glucose glycogen Gallbladder Store bile gallbladder common bile duct a. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. bile common hepatic duct pancreatic duct pancreatic juice pancreas central vein b. bile duct bile canals branch of hepatic artery branch of hepatic portal vein Figure 9.8 Accessory organs of the digestive system. 12

9.4 The Accessory Organs and Regulation of Secretions Liver disorders Hepatitis Cirrhosis 13

9.4 The Accessory Organs and Regulation of Secretions GI Hormones Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. gallbladder liver stomach pancreas Figure 9.9 Hormonal control and regulation of digestion. duodenum blood vessel secretin CCK gastrin 14

Figure 41.19a 1 Liver GI Hormones Food Stomach Gallbladder Gastric juices Gastrin Pancreas Duodenum of small intestine Key Stimulation Inhibition 15

GI Hormones 2 Bile Chyme CCK HCO 3, enzymes Key Stimulation Inhibition Secretin CCK 16

Figure 41.19c GI Hormones 3 Secretin and CCK Gastric juices Key Stimulation Inhibition 17

9.5 The Large Intestine and Defecation The large intestine Includes the cecum, colon, rectum, and anal canal. Diameter Cecum = appendix: 18

9.5 The Large Intestine and Defecation The large intestine Functions to 19

9.5 The Large Intestine and Defecation The large intestine Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. transverse colon ascending colon small intestine descending colon cecum orifice of appendix vermiform appendix rectum sigmoid colon internal anal sphincter anal canal external anal sphincter anus Figure 9.10 The regions of the large intestine. 20

9.5 The Large Intestine and Defecation Disorders of the colon and rectum Diarrhea Constipation Hemorrhoids Diverticulosis Irritable bowel syndrome (IBS Inflammatory bowel disease/colitis (IBD) Polyps and cancer 21

9.1 Overview of Digestion An overview of the digestive system Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Accessory organs Salivary glands secrete saliva which contains digestive enzyme for carbohydrates Digestive tract organs Mouth teeth chew food; tongue tastes and pushes food for chewing and swallowing 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 Gallbladder stores bile from liver; sends it to the small intestine Pancreas produces pancreatic juice ; contains digestive enzymes, and sends it to the small intestine; produces insulin and secretes it into the blood after eating Stomach secretes acid and digestive enzyme for protein; churns, mixing food with secretions, and sends chyme to small intestine Small intestine mixes chyme with digestive enzymes for final breakdown; absorbs nutrient molecules into body; secretes digestive hormones into blood Large intestine absorbs water and salt to form feces Figure 9.1 Organs of the GI tract and accessory structures of digestion. Rectum stores and regulates elimination of feces Anus 22

Figure 41.20 Transport of glucose into body cells and storage of glucose as glycogen Homeostasis: 70 110 mg glucose/ 100 ml blood Stimulus: Blood glucose level rises after eating. Pancreas secretes insulin. Breakdown of glycogen and release of glucose into blood Stimulus: Blood glucose level drops below set point. Pancreas secretes glucagon. 23

Other hormones associated with eating Satiety center Leptin PYY Ghrelin Insulin 24

Digestive system secretion & nutrient absorption Veins to heart Hepatic portal vein Lymphatic system Liver Mouth Esophagus Stomach Lipids Absorbed food (except lipids) Absorbed water Secretions from salivary glands Secretions from gastric glands Small intestine Secretions from liver Secretions from pancreas Large intestine Anus Rectum 25

9.6 Nutrition and Weight Control What is obesity? What is BMI? 26

9.6 Nutrition and Weight Control To understand weight and nutrition, we first have to understand nutrients Nutrients are components of food that are needed to perform physiological body functions. Nutrients include carbohydrates. proteins. lipids. minerals. vitamins. 27

9.6 Nutrition and Weight Control Carbohydrates Simple sugars primary energy source Refined grains fiber and vitamins are removed white bread, cake, and cookies Complex carbohydrates beans, whole-grain products, nuts, and fruits Refined sugars & fructose sweeteners may contribute to obesity. Increases insulin secretion insulin resistance Type 2 diabetes and increased fat metabolism. Increase fat deposition may increase the risk of coronary heart disease, liver diseases, and certain cancers 28

9.6 Nutrition and Weight Control How can you reduce high-glycemic index carbohydrates? 29

9.6 Nutrition and Weight Control 8 essential amino acids Proteins Complete proteins have: animals such as meat and dairy Nonanimal sources: tofu, soymilk, and other processed food from soybeans Incomplete proteins lack: legumes, nuts, grains 30

9.6 Nutrition and Weight Control Can proteins be harmful? 31

9.6 Nutrition and Weight Control Lipids Lipids include fats, oils, and cholesterol. Saturated fats Essential fatty acids 32

9.6 Nutrition and Weight Control Choosing the most healthy fat and oil Figure 9.14 Saturated and unsaturated fatty acids. 33

9.6 Nutrition and Weight Control Can lipids be harmful? 34

9.6 Nutrition and Weight Control How can you reduce bad fats and cholesterol in your diet? 35

9.6 Nutrition and Weight Control A summary of minerals 36

9.6 Nutrition and Weight Control Vitamins 37

9.6 Nutrition and Weight Control Fat-soluble vitamins 38

9.6 Nutrition and Weight Control Water-soluble vitamins 39

9.6 Nutrition and Weight Control Antioxidants 40

9.6 Nutrition and Weight Control Height What is your BMI? Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6 6 6 4 underweight healthy weight overweight obese Body Mass Index (BMI) 19 25 30 6 2 6 0 5 10 5 8 5 6 5 4 5 2 5 0 4 10 50 75 100 125 150 175 200 225 250 275 Weight (lb) Source: U.S. Department of Agriculture: Dietary Guidelines for Americans, 2005 Figure 9.11 The body mass index chart. 41

9.6 Nutrition and Weight Control Why should we be concerned with obesity? 42

9.6 Nutrition and Weight Control Why should we be concerned with obesity? It is associated with: an increased risk of premature death type 2 diabetes Hypertension CVD Stroke gallbladder disease respiratory dysfunction Osteoarthritis certain cancers. 43

9.6 Nutrition and Weight Control Searching for the magic weight-loss bullet Trendy diet programs Pritikin diet: Atkins: Zone and South beach diets: Caveman, or Paleo Diet Prescription drugs 44

9.6 Nutrition and Weight Control Searching for the magic weight-loss bullet Surgical procedures Gastroplasty: Gastric bypass: Gastric banding: Liposuction: 45

9.6 Nutrition and Weight Control Eating disorders are associated with body image Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Anorexia nervosa b. Bulimia nervosa c. Muscle dysmorphia a: Ted Foxx/Alamy RF; b: Donna Day/Stone/Getty Images; c: Corbis RF Figure 9.16 The characteristics of different eating disorders. 46

9.6 Nutrition and Weight Control Anorexia nervosa: Eating disorders Bulimia nervosa: 47

9.6 Nutrition and Weight Control Binge-eating disorder: Eating disorders Muscle dysmorphia: 48