This document provides an overview of the digestive system, including the organs and processes involved in digestion. It discusses the anatomy and functions of the mouth, pharynx, esophagus, stomach, pancreas, liver, and gallbladder. The digestive system breaks down food mechanically and chemically and absorbs nutrients to provide energy for cell activities. Accessory organs like the liver, pancreas and gallbladder produce enzymes and bile to further break down food in the small intestine so nutrients can be absorbed and waste eliminated.

1. BIOL 2074: Anatomy & Physiology II Chapter 17 Digestive System Brenda Holmes MSN/Ed, RN Associate Professor Biology South Arkansas Community College Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display

3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anus ACCESSORY ORGANS Salivary glands Secrete saliva, which contains enzymes that initiate breakdown of carbohydrates Liver Produces bile, which emulsifies fat Gallbladder Stores bile and introduces it into small intestine Pancreas Produces and secretes pancreatic juice, containing digestive enzymes and bicarbonate ions, into small intestine ALIMENTARY CANAL Mouth Mechanical breakdown of food; begins chemical digestion of carbohydrates Pharynx Connects mouth with esophagus Esophagus Peristalsis pushes food to stomach Stomach Secretes acid and enzymes; mixes food with secretions to begin enzymatic digestion of proteins Small intestine Mixes food with bile and pancreatic juice; final enzymatic breakdown of food molecules; main site of nutrient absorption Large intestine Absorbs water and electrolytes to form feces Rectum Regulates elimination of feces

5. Structure of the Wall Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Intestinal gland Lacteal Epithelium Mucous gland in submucosa Mucosa Circular muscle Longitudinal muscle Circular muscle Longitudinal muscle Serosa Artery Mesentery Circular fold Mucosa Submucosa Serosa Capillaries Lacteal Microvilli Nucleus Goblet cell Vein Villi Lymph nodule Nerve plexuses Muscular layer Simple columnar epithelium

7. Movements of the Tube Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (c) (a) Movement of contents (b) Digesting material Wave of contraction

14. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b: © Nick Koudis/Getty Images Incisors Canine (cuspid) Canine (cuspid) Molars Incisors (a) Molars (b) Canines Premolars (bicuspids) Premolars (bicuspids) Second premolars First premolars Lateral incisors Central incisors

15. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Crown Gingiva Root canal Cementum Root Dentin Enamel Alveolar process Periodontal ligament Pulp cavity

16. 17.1 Clinical Application Dental Caries

19. Major Salivary Glands Sublingual gland Mandible (cut) Parotid gland Masseter muscle Submandibular gland Tongue Submandibular duct Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Duct (a) Serous cell Duct Mucous cell (c) Serous cell Duct (b) Serous cell Mucous cell a: © The McGraw-Hill Companies, Inc./Al Telser, photographer; figure b: © Biophoto Associates/Photo Researchers, Inc.; figure c: © The McGraw-Hill Companies, Inc./Al Telser, photographer Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

23. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superior Middle Inferior Tongue Epiglottis Trachea Esophagus Soft palate Larynx Epiglottis Hyoid bone Esophagus Larynx Tongue Peristaltic wave Stomach Esophagus Food mass Nasopharynx with mucosa removed to show muscles Pharyngeal constrictor muscles: Hard palate Food mass (a) The tongue forces food into the pharynx. Soft palate Superior pharyngeal constrictor muscles Food mass (c) Superior constrictor muscles contract and force food into the esophagus. Food mass Inferior pharyngeal constrictor muscles (b) The soft palate, hyoid bone, and larynx are raised, the tongue is pressed against the palate, the epiglottis closes, and the inferior constrictor muscles relax so that the esophagus opens. (d) Peristaltic waves move food through the esophagus to the stomach.

24. Esophagus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Esophagus Diaphragm Stomach Esophageal hiatus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Mucosa Lumen Submucosa © Ed Reschke Muscular layer

26. Parts of the Stomach Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fundus Body Pylorus Pyloric opening Duodenum Cardia Esophagus Esophagus Esophagus (b) (a) Circular fibers Longitudinal fibers Oblique fibers Longitudinal fibers Pyloric sphincter Lesser curvature Lower esophageal sphincter Pyloric canal Pyloric antrum Gastric folds (rugae) Greater curvature

27. Parts of the Stomach Pyloric sphincter Duodenum Pylorus Fundus Gastric folds Body © Dr. Kent M. Van De Graaff Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

29. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Gastric pits Chief cell (a) (b) Parietal cell Gastric gland Mucous cell Mucosa Submucosa Serosa Mucous cell Gastric pit Parietal cell Chief cell Portion of a gastric gland Portion of a gastric gland Muscle layers b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

31. Regulation of Gastric Secretions Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 2 3 4 Stimulation Bloodstream Release into bloodstream Parasympathetic preganglionic nerve fiber (in vagus nerve) Gastrin stimulates gastric glands to release more gastric juice Parasympathetic postganglionic impulses stimulate the release of gastric juice from gastric glands Impulses stimulate the release of gastrin

34. Mixing and Emptying Actions Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stomach Chyme Duodenum (a) (b) (c) Pyloric sphincter relaxed Pyloric sphincter contracted Food entering

35. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. From CNS 4 1 2 3 Nerve impulses inhibit peristalsis in stomach wall Duodenum fills with chyme Sensory stretch receptors are stimulated Sensory nerve impulses travel to central nervous system To CNS Vagus nerve

36. 17.2 Clinical Application Oh, My Aching Stomach!

38. Structure of the Pancreas Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Right hepatic duct Left hepatic duct Cystic duct Common hepatic duct Bile duct Bile duct Gallbladder Sphincter muscles Head of pancreas Duodenum Major duodenal papilla Intestinal lumen Pancreatic duct Pyloric sphincter Minor duodenal papilla Major duodenal papilla Tail of pancreas Pancreatic duct Hepatopancreatic sphincter Hepatopancreatic ampulla

40. Regulation of Pancreatic Secretion Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bloodstream 1 5 4 3 2 Stimulation of effector organ Acidic chyme enters duodenum Bicarbonate ions neutralize acidic chyme Intestinal mucosa releases secretin into bloodstream Secretin stimulates pancreas to secrete bicarbonate ions Hormonal signals released into bloodstream Pancreatic juice rich in bicarbonate ions passes down pancreatic ducts to the duodenum

42. Liver Structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Right lobe Coronary ligament Inferior vena cava Left lobe Inferior vena cava Right lobe Gallbladder Quadrate lobe Cystic duct Left lobe Hepatic duct Hepatic artery Bile duct Caudate lobe Gallbladder (b) (a) Round ligament Hepatic portal vein Falciform ligament

43. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bile duct Branch of hepatic artery Plates of liver cells Central vein Bile canaliculi Bile ductule Bile duct Sinusoids (b) (a) (c) Branch of hepatic portal vein Hepatic sinusoids Branches of hepatic artery Branch of hepatic portal vein c: © The McGraw-Hill Companies, Inc./Al Telser, photographer

44. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bile duct Bile ductule Bile canaliculi Kupffer cell Hepatic cells Branch of hepatic portal vein Branch of hepatic artery Hepatic sinusoids Blood flow into liver Central vein (blood flow out of liver)

47. 17.1 From Science to Technology Replacing the Liver

49. 17.3 Clinical Application Hepatitis

50. Gallbladder Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

51. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Carroll Weiss/Camera M.D. Studios

52. Regulation of Bile Release Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 4 5 Gallbladder Bile duct Cystic duct Duodenum 3 Bloodstream 2 Chyme with fat enters duodenum Cells from the intestinal mucosa secrete the hormone cholecystokinin (CCK) into the bloodstream Hormonal signals released into bloodstream Stimulation of effector organ Pancreatic duct Hepatopancreatic sphincter relaxes and bile enters duodenum Bile passes down the cystic duct and bile duct to duodenum CCK stimulates muscular layer of gallbladder wall to contract Common hepatic duct

55. 17.4 Clinical Application Gallbladder Disease

57. Parts of the Small Intestine Stomach Jejunum Duodenum Ascending colon Mesentery Appendix Cecum Ileum Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

58. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stomach Small intestine © Armed Forces Institute of Pathology

59. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Liver Stomach Gallbladder Transverse colon underneath Greater omentum

60. Structure of the Small Intestinal Wall Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lacteal Blood capillary network Intestinal gland Goblet cells Simple columnar epithelium Venule Arteriole Lymph vessel Villus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lumen Intestinal gland Villus © The McGraw-Hill Companies, Inc./Al Telser, photographer

61. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Microvilli Cell membrane Mitochondrion Golgi apparatus Nucleolus Nucleus (a) Lumen Microvilli (b) Rough endoplasmic reticulum Cytoplasm of epithelial cell b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

62. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Submucosa Circular muscle Longitudinal muscle Serosa (a) (b) Plicae circulares Muscular layer Villi

68. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Maltose Glucose Monosaccharides Disaccharide Glucose  H H O Maltase Maltase  HO H O OH OH H O H H HO H O OH HO H O H 2 O Water H N C H H Amino acid Amino acid Dipeptidase   R C H N O C R H H N C H H R C OH O H N C H H R C OH O C OH O Dipeptidase H 2 O Dipeptide (from protein digestion) Water Lipase H C HO HO HO H C H H C H C C 17 H 35 COO H H C H 3H 2 O Lipase + + Fatty acids Glycerol Fat C H C H O C O C O C 17 H 35 COO C 17 H 35 COO Water C 17 H 35 C C 17 H 35 C C 17 H 35 C OH OH OH

69. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fatty acids Lacteal Nucleus Chylomicrons 1 2 3 4 5 Lymph To blood Lymph in lacteal transports chylomicrons away from intestine Chylomicrons leave epithelial cell and enter lacteal Fats collect in clusters encased in protein to form chylomicrons Fatty acids are used to synthesize fats in endoplasmic reticulum Fatty acids resulting from fat digestion enter epithelial cell Endoplasmic reticulum Lumen of intestine Epithelial cell

72. Parts of the Large Intestine Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anal canal Sigmoid colon Haustra Descending colon Rectum Appendix Cecum Orifice of appendix Ileocecal sphincter Ascending colon Serous layer Mucous membrane Transverse colon Muscular layer Ileum Hepatic flexure Tenia coli Splenic flexure Epiploic appendage

73. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Jim Wehtje/Getty Images

74. Structure of the Large Intestinal Wall © Ed Reschke/Peter Arnold Lumen Submucosa Muscular layer Serosa Mucosa Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

78. 17.5 Clinical Application Disorders of the Large Intestine