CHAPTER 29 The Digestive System © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-2 Learning Outcomes 29.1 List the functions of the digestive system 29.2 Trace the pathway of food through the alimentary canal 29.3 Describe the structure and functions of the mouth, teeth, tongue, and salivary glands 29.4 Describe the structure and function of the pharynx © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-3 Learning Outcomes (cont.) 29.5 Describe the swallowing process 29.6 Describe the structure of the esophagus and tell how it propels food into the stomach 29.7 Describe the structure and functions of the stomach 29.8 List the substances secreted by the stomach and give their functions © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-4 Learning Outcomes (cont.) 29.9 Describe the structure and functions of the small intestine 29.10 List the substances secreted by the small intestine and describe the importance of each 29.11 Describe the structure and functions of the large intestine, including the anal canal and rectum 29.12 Explain the structures and functions of the liver, gallbladder, and pancreas © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-5 Learning Outcomes (cont.) 29.13 List the substances released by the liver, gallbladder, and pancreas into the small intestine and give the function of each secretion 29.14 Tell what types of nutrients are absorbed by the digestive system and where they are absorbed 29.15 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the digestive system © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-6 Introduction • Digestion – Mechanical and chemical breakdown of foods into forms that body cells can absorb – The organs of the digestive system carry out digestion • Two categories – Alimentary canal organs – Accessory organs © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-7 Alimentary Canal • Wall of alimentary canal – Mucosa • • • Innermost layer; epithelial tissue Secretes enzymes and mucus into lumen Absorbs nutrients – Submucosa • • Inferior to mucosa; loose connective tissue, blood vessels, glands, and nerves Blood vessels carry away absorbed nutrients – Muscular layer • • Just outside submucosa; layers of smooth muscle Contracts to move materials through the canal © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-8 Alimentary Canal (cont.) – Serosa • Double-walled outermost layer: peritoneum – Visceral peritoneum » » Innermost wall of serosa Secretes serous fluid to keep outside of canal moist – Parietal peritoneum » • Abdominal lining Movements – Churning – mixes substances in the canal – Peristalsis – propels substances through the tract © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-9 Apply Your Knowledge What are the layers of the wall of the alimentary canal and what they do? ANSWER: The layers are: Mucosa: innermost layer; secretes enzymes and mucus into the canal and absorbs nutrients Submucosa: inferior to the mucosa; carries away absorbed nutrients Muscular layer: just outside the submucosa; contracts to move materials through the canal Serosa: double-walled outer layer; secretes serous fluid to keep outside of canal moist Bravo © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-10 The Mouth • Buccal cavity • Mechanical digestion – Takes in food and reduces its size by chewing • Starts chemical digestion – Saliva contains the enzyme amylase, which breaks down carbohydrates © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-46 Apply Your Knowledge True or False: ANSWER: T Carbohydrates are starches, simple sugars, and cellulose _ liver F Excess glucose is stored in the gallbladder as glycogen _ most F Triglycerides are the least abundant lipids _ T Linoleic acid is an essential fatty acid _ fat-soluble F A, D, E and K are water-soluble vitamins _ T Minerals are used by cells to make enzymes _ © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-47 Aging and the Digestive System • Decreased motility – GERD • Decreased ability to detoxify blood • Decreased absorption • Sense of taste altered • More likely to develop ulcers and cancers • Dietary changes due to – Isolation – Depression © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-48 Common Diseases and Disorders Disease/Disorder Description Appendicitis Inflammation of the appendix; can be lifethreatening if not treated promptly Cirrhosis Chronic liver disease; normal tissue is replaced with nonfunctional scar tissue Colitis Inflammation of the large intestine; can be acute or chronic Colorectal cancer Arises from lining of rectum or colon; curable if treated early © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-49 Common Diseases and Disorders (cont.) Disease/Disorder Description Constipation Difficult defecation Crohn’s disease Inflammatory bowel disease; typically effects small intestine Diarrhea Watery and frequent feces; usually self-limiting Diverticulosis Abnormal pouches in the intestinal wall; no inflammation present © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-50 Common Diseases and Disorders (cont.) Disease/Disorder Description Diverticulitis Inflammation of diverticuli (abnormal pouches in intestinal wall) of the intestine Gastritis Inflammation of the stomach lining; “upset stomach” Heartburn Gastroesophageal reflux disease (GERD); stomach acids push into esophagus Hemorrhoids Varicose veins of rectum or anus Hepatitis Inflammation of the liver; various types © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-51 Common Diseases and Disorders (cont.) Disease/Disorder Description Hiatal hernia Portion of stomach protrudes into the chest through an opening (usually the esophageal hiatus) in the diaphragm Inguinal hernia Portion of large intestine protrudes in the inguinal canal (where thigh and trunk meet) or, in males, into the scrotum Oral cancer Usually involves the lips or tongue but can occur anywhere in the mouth; tends to spread rapidly © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-52 Common Diseases and Disorders (cont.) Disease/Disorder Description Pancreatic cancer Fourth leading cause of cancer deaths in the U.S Stomach cancer Commonly in cardiac portion of the stomach; occurs more frequently in Japan, Chili, and Iceland Stomach ulcers Breakdown in lining of the stomach; can be caused by bacteria (H pylori) or smoking, alcohol, excessive aspirin use, and hypersecretion of stomach acid © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-53 Apply Your Knowledge Matching: ANSWER: E Inflammation of the large intestine _ A Heartburn D Inflammatory bowel disease _ B Hemorrhoids F Watery and frequent feces _ C Difficult defecation _ C Constipation G Inflammation of the stomach lining _ E Colitis D Crohn’s disease H Inflammation of pouches in the intestinal wall F Diarrhea _ A GERD _ G Gastritis B Varicose veins of rectum _ H Diverticulitis © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-54 In Summary 29.1 The digestive system uses mechanical and chemical mechanisms to break down food into forms that the body’s cells can use 29.2 The pathway of food through the alimentary canal starts with the mouth through the pharynx, esophagus, stomach, small intestines, large intestines, and anal canal 29.3 The mouth takes in food and the teeth assist in reducing its size through chewing The tongue mixes food and holds it between the teeth The salivary glands produce saliva to assist in moistening and breaking down food © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-55 In Summary (cont.) 29.4 The pharynx is a long muscular tube extending from behind the nose to the esophagus, connecting the oral and nasal cavities It also acts to push food into the esophagus 29.5 The soft palate rises, closing the opening between the nasal and oral cavities The epiglottis covers the laryngeal opening Food is forced into the oropharynx by the tongue, and the pharynx contracts, pushing food to the esophagus 29.6 The esophagus is a muscular tube that pushes food toward the stomach through muscular contractions At the end of the esophagus is the cardiac sphincter, the entrance to the stomach © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-56 In Summary (cont.) 29.7 The stomach is in the LUQ It receives food, mixes it with gastric juices, starting protein digestion, and moves food into the small intestine The stomach has four regions: cardiac region, fundus, body, and pylorus 29.8 The stomach’s gastric glands include mucous cells that secret mucus, chief cells that secret pepsinogen, and parietal cells that secrete hydrochloric acid and intrinsic factor 29.9 The small intestine carries out most of the nutrient absorption The sections of the small intestine are, in order, duodenum, jejunum, and ileum © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-57 In Summary (cont.) 29.10 The small intestine secretes peptidases to digest protein; sucrase, maltase and lactase, which digest sugars; and intestinal lipase, which digests fats 29.11 The components of the large intestine are the cecum with its vermiform appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal ending in the anus The large intestine’s primary job is to rid the body of solid waste by defecation © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-58 In Summary (cont.) 29.12The liver is in the RUQ It stores vitamins and iron and produces macrophages to fight infection The gallbladder stores the bile produced by the liver The pancreas produces pancreatic juices that assist in carbohydrate, lipid, and protein digestion 29.13The liver secretes bile for fat digestion Bile is released by the gallbladder for fat digestion Pancreatic juices contain pancreatic amylase for carbohydrate digestion; lipase for lipid digestion; nucleases to digest nucleic acids; and trypsin, chymotrypsin, and carboxypeptidase to digest proteins © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-59 In Summary (cont.) 29.14 Nutrients absorbed by the body include carbohydrates, proteins, lipids, vitamins, minerals, and water Most of the absorption takes place in the small intestine 29.15 Common diseases and disorders of the digestive system include inflammatory disorders such as appendicitis and colitis; cancers including colorectal, oral, and pancreatic cancers; as well as common symptoms such as diarrhea, constipation, and GERD For more detailed information regarding these and other common disorders, please see the Pathophysiology section at the end of this chapter © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29-60 End of Chapter 29 Take all that is given whether wealth, love or language; nothing comes by mistake and with good digestion all can be turned to health ~ George Herbert © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed [...]... -Hill Com panie s, Inc A ll rights reserv ed 29- 27 The Small Intestine (cont.) • Lining of small intestine – Microvilli – increase surface area – Intestinal glands • Mucus and water • Enzymes – Peptidases – digest proteins – Sucrase, maltase, and lactase – digest sugars – Intestinal lipase – digests fats • Primary controls – Parasympathetic nervous system – Stretching of intestinal wall © 2011 T he... pieces – Cuspids – tear tough food – Bicuspids and molars – grind food • Salivary glands – Cells • Serous • Mucous – Glands • Parotid • Submandibular • Sublingual © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29- 14 Apply Your Knowledge Matching: ANSWER: B Buccal cavity _ A Saliva D Roof of mouth _ B Mouth E Grind food _ C Bolus F Adenoids _ D Palate A Water, enzymes, and mucus... Circular bands of muscle _ E Pharynx © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29- 20 The Stomach • Below the diaphragm in the upper left quadrant of the abdominal cavity • Functions – Receive food from esophagus – Mix bolus with gastric juice – Start protein digestion – Move food into small intestine • Sections – – – – Cardiac region Fundus Body Pylorus • Pyloric sphincter – Controls... reserv ed 29- 12 The Mouth (cont.) • Palate – Roof of mouth – Separates oral cavity from nasal cavity – Uvula – portion of soft palate that hangs down in throat • Lymph tissue – Palatine tonsils (oropharynx) – Pharyngeal tonsils – adenoids (nasopharynx) © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29- 13 The Mouth (cont.) • Teeth – decrease size of food particles – Incisors – bite off... and mucus _ E Bicuspids B Mass of food mixed with saliva and mucus _ F Pharyngeal gland © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29- 15 Pharynx • Throat • Functions – Connects nasal cavity with oral cavity for breathing – Pushes food into esophagus • Divisions – Nasopharynx • Behind nasal cavity – Oropharynx • Behind oral cavity – Laryngopharynx • Behind larynx • Continues as... reserv ed 29- 32 The Rectum and Anal Canal • Rectum – off sigmoid colon • Anal canal – Last few centimeters of rectum – Opening to outside of body is the anus Large Intestine © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29- 33 The Rectum and Anal Canal (cont.) • Feces – Leftover chyme – Consists of undigested solid materials, little water, ions, mucus, cells of intestinal lining, and bacteria... ll rights reserv ed 29- 36 The Liver • Lobular organ in right upper quadrant – Large right lobe and smaller left lobe • Hepatic lobules – contain macrophages • Hepatocytes – process nutrients in blood and make bile • Part of liver’s function – Store vitamins and iron © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29- 37 The Liver (cont.) • Hepatic portal vein – carries blood from digestive... mix it with gastric juice, start protein digestion, and move food into the small intestine It also absorbs alcohol, water, and some drugs Right Answer! © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 29- 25 The Small Intestine • Tubular organ extending from the stomach to the large intestine • Functions – Digestion – Absorption of nutrients • Duodenum – C-shaped – Short • Jejunum – Coiled.. .29- 11 The Mouth (cont.) • Cheeks hold food in mouth • Lips – sensory nerve fibers that judge temperature of food • Tongue – Skeletal muscles covered by mucous membrane – Lingual frenulum – holds tongue to floor of mouth – Mixes food, holds food between teeth, contains taste buds – Lingual tonsils – lymphatic tissue destroys bacteria and viruses on back of tongue © 2011... McGraw -Hill Com panie s, Inc A ll rights reserv ed 29- 21 The Stomach (cont.) • Lining of stomach – Rugae – folds of the inner lining – Gastric glands • Mucous cells – secrete mucus to protect the lining • Chief cells – secrete pepsinogen pepsin, which digests protein • Parietal cells – Hydrochloric acid needed to convert pepsinogen to pepsin – Intrinsic factor needed for vitamin B12 absorption