End Show Slide 1 of 36 Copyright Pearson Prentice Hall 38–2 The Process of Digestion

End Show 38–2 The Process of Digestion Slide 2 of 36 Copyright Pearson Prentice Hall 38–2 The Process of Digestion Mouth Salivary glands Stomach Pancreas Large intestine Small intestine Pharynx Esophagus Liver Gallbladder Rectum The Digestive System

End Show 38–2 The Process of Digestion Slide 3 of 36 Copyright Pearson Prentice Hall The Mouth The function of the digestive system is to convert foods into simpler molecules that can be absorbed and used by the body.

End Show 38–2 The Process of Digestion Slide 4 of 36 Copyright Pearson Prentice Hall Human Digestive System Tongue – taste buds, swallow, help chew Teeth – mechanical digestion Salivary glands – saliva, lubricate, carb’s Pharynx – back of throat, pathways cross Esophagus – food tube to stomach Epiglottis – covers trachea to prevent choking Peristalsis – wave of muscular contractions

End Show 38–2 The Process of Digestion Slide 5 of 36 Copyright Pearson Prentice Hall The Esophagus Peristalsis: The cardiac sphincter closes the esophagus after food has passed to the stomach. Esophagus Bolus Stomach Muscles contracted

End Show 38–2 The Process of Digestion Slide 6 of 36 Copyright Pearson Prentice Hall The Stomach Muscular Organ – 3 layers of muscle Churns food – mechanical digestion Sphincter muscles close off both ends Stores food for up to 4 hours Digests proteins Gastric glands – produce pepsin & HCl Chyme – mixture of stomach contents

End Show 38–2 The Process of Digestion Slide 7 of 36 Copyright Pearson Prentice Hall The Small Intestine Small Int – 20’long, 1” wide, digests all foods and absorbs all nutrients Intestinal glands produce some enzymes Villi – fingerlike projections for absorption Large Int – 4’ long, 2” wide, absorbs water Rectum – stores feces for elimination Anus – final sphincter of digestive track

End Show 38–2 The Process of Digestion Slide 8 of 36 Copyright Pearson Prentice Hall The Small Intestine Accessory Structures of Digestion Liver Gallbladder Duodenum Bile duct Pancreas Pancreatic duct To rest of small intestine

End Show 38–2 The Process of Digestion Slide 9 of 36 Copyright Pearson Prentice Hall The Small Intestine Accessory Structures of Digestion Liver – largest gland in body Liver produces bile to assist fat digestion Gall Bladder – stores bile, delivers to sm.int. Liver stores sugar & fat soluble vitamins Pancreas – produces enzymes for all foods Also produces insulin to help cells absorb glucose.

End Show 38–2 The Process of Digestion Slide 10 of 36 Copyright Pearson Prentice Hall The Stomach

End Show 38–2 The Process of Digestion Slide 11 of 36 Copyright Pearson Prentice Hall The Small Intestine Most chemical digestion and absorption of food occurs in the small intestine.

End Show 38–2 The Process of Digestion Slide 12 of 36 Copyright Pearson Prentice Hall Absorption in the Small Intestine Villi - fingerlike projections of the small intestine. They provide an enormous surface area. Nutrients are absorbed into the cells lining the villi.

End Show 38–2 The Process of Digestion Slide 13 of 36 Copyright Pearson Prentice Hall The Small Intestine Small intestine Circular folds Villi Villus Epithelial cells Capillaries Lymph vessel Vein Artery Absorption in the Small Intestine

End Show 38–2 The Process of Digestion Slide 14 of 36 Copyright Pearson Prentice Hall The Large Intestine The large intestine absorbs water from the chyme. Concentrated wastes are stored in the rectum.

End Show 38–2 The Process of Digestion Slide 15 of 36 Copyright Pearson Prentice Hall Digestive System Disorders Ulcer – hole in stomach or intestines Appendicitis – infection of appendix Gallstones – cholesterol in gall bladder Malnutrition – over, under, poor (deficiencies) Obesity – overweight, 25% US population –Leads to health problems:diabetes, heart disease Anorexia – severe underweight

End Show Slide 16 of 36 Copyright Pearson Prentice Hall 38–2 Food is moved through the esophagus into the stomach by a.air pressure. b.muscle contractions. c.gravity. d.swallowing.

End Show Slide 17 of 36 Copyright Pearson Prentice Hall 38–2 A gland that has both endocrine and exocrine functions is the a.liver. b.spleen. c.pancreas. d.gallbladder.

End Show Slide 18 of 36 Copyright Pearson Prentice Hall 38–2 The enzyme in saliva that begins the digestion of starch is a.amylase. b.pepsin. c.lysozyme. d.peptidase.

End Show Slide 19 of 36 Copyright Pearson Prentice Hall 38–2 Stomach muscles contract to churn and mix stomach fluids and food, producing a mixture known as a.chyme. b.amylase. c.bile. d.acid.

End Show Slide 20 of 36 Copyright Pearson Prentice Hall 38–2 Absorption of vitamins, minerals, and digested food molecules takes place in the a.stomach. b.small intestine. c.large intestine. d.duodenum.