1. PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 22 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Digestive System PART 1

2. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Alimentary Canal – epithelial mucous membrane, submucosa, muscular layers,(smooth muscle longitudinal and circular), serosa – visceral peritoneum, superficial covering (doesn’t cover the esophagus) Mouth – tongue, teeth, salivary glands, palate, tonsils Pharynx - throat Esophagus – canal between mouth and stomach, peristalsis Stomach – digests food, 3 muscular layers, lined with epithelium Duodenum – first 9 inches of small intestine, bile and pancreatic bicarbonate enter to emulsify fat and reduce acidity Liver – accessory organ of digestion – turns crude food into molecular food ready for absorption by somatic cells Pancreas – accessory organ of digestion and endocrine organ to regulate glucose in blood Jejunum – second 13 inches of small intestine Ileum – the entire small intestine, lined with specialized epithelium for absorption of food molecules Large Intestine – last 4 feet of intestine for water reabsorption and breakdown of carbohydrates by bacteria Anal Canal – for excretion of waste

3. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Nine Regions of Anterior Abdominal Surface  How regions relate to abdominal viscera Figure 22.4b

4. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Abdominal Quadrants  A simpler scheme defining four quadrants Figure 22.4c

5. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Mouth and Associated Organs  The mouth – oral cavity  Mucosal layer  Stratified squamous epithelium  Lamina propria  The lips and cheeks  Formed from orbicularis oris and buccinator muscles, respectively

6. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Mouth Figure 22.12a

7. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.12b Anatomy of the Mouth  The labial frenulum  Connects lips to gum  The palate  Forms the roof of the mouth

8. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Tongue  Interlacing fascicles of skeletal muscle  Grips food and repositions it  Helps form some consonants  Intrinsic muscles – within the tongue  Extrinsic muscles – external to the tongue  Lingual frenulum  Secures tongue to floor of mouth

9. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Superior Surface of the Tongue  Tongue papillae  Filiform papillae – no taste buds  Fungiform papillae  Circumvallate papillae  Sulcus terminalis  Marks border between mouth and pharynx  Posterior 1/3 of tongue lies in oropharynx  Lined with lingual tonsil

10. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Superior Surface of the Tongue Figure 22.13

11. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Teeth  Deciduous teeth – 20 teeth  First appear at 6 months of age  Permanent teeth – 32 teeth  Most erupt by the end of adolescence  Dental formula – shorthand  Way to indicate number and position of teeth  2I, 1C, 2P, 3M (incisors, canine, pre-molar and molar)

12. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Teeth Figure 22.14

13. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Tooth Structure  Longitudinal section of tooth in alveolus Figure 22.15

14. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Salivary Glands  Produce saliva  Compound tubuloalveolar glands  Parotid glands  Parotid duct – parallel to zygomatic arch  Contains only serous cells  Submandibular glands  Lies along medial surface of mandible  Sublingual glands  Lies in floor of oral cavity  Contains primarily mucous cells

15. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Salivary Glands Figure 22.16

16. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.1 The Alimentary Canal and Accessory Digestive Organs

17. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Segmentation  Rhythmic local contractions of the intestine  Mixes food with digestive juices Figure 22.3b

18. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Peristalsis  Major means of propulsion  Adjacent segments of the alimentary canal relax and contract Figure 22.3a

19. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Digestive Processes Figure 22.2

20. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Mesenteries  Greater omentum – a “fatty apron” of peritoneum  Greater omentum and transverse colon reflected Figure 22.10c

21. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Mesenteries  Lesser omentum attaches to lesser curvature of stomach Figure 22.10b

22. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Pharynx  Oropharynx and laryngopharynx  Passages for air and food  Lined with stratified squamous epithelium  External muscle layer  Consists of superior, middle, and inferior pharyngeal constrictors

23. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Esophagus  Gross anatomy – muscular tube  Begins as a continuation of the pharynx  Joins the stomach inferior to the diaphragm  Cardiac sphincter – closes lumen to prevent stomach acid from entering esophagus

24. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Esophagus  Microscopic anatomy  Epithelium is stratified squamous epithelium  When empty – mucosa and submucosa in longitudinal folds  Mucous glands – primarily compound tubuloalveolar glands  Muscularis externa  Skeletal muscle first third of length  Adventitia – most external layer

25. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Microscopic Structure of the Esophagus Figure 22.17a, b

26. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Stomach  Site where food is churned into chyme  Secretion of pepsin begins protein digestion  Functions under acidic conditions  Food remains in stomach approximately 4 hours

27. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Stomach Figure 22.18a

28. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Stomach Figure 22.18b

29. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Microscopic Anatomy of the Stomach  Muscularis has three layers  Circular and longitudinal layers and oblique layer  Epithelium is simple columnar epithelium  Mucosa dotted with gastric pits  Gastric glands – deep to gastric pits

30. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Microscopic Anatomy of the Stomach  Gastric glands of fundus and body  Mucous neck cells  Secrete a special mucus  Parietal (oxyntic) cells  Secrete hydrochloric acid and gastric intrinsic factor  Chief (zymogenic) cells  Secrete pepsinogen

31. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Stomach – Microscopic Anatomy Figure 22.19a–d

32. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Small Intestine – Gross Anatomy  Longest portion of the alimentary canal  Site of most enzymatic digestion and absorption  Three subdivisions  Duodenum  Jejunum  Ileum

33. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Duodenum  Receives digestive enzymes and bile  Main pancreatic duct and common bile duct enter duodenum  Sphincters control entry of bile and pancreatic juices

34. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Duodenum and Related Organs Figure 22.20

35. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Small Intestine – Microscopic Anatomy  Modifications for absorption  Circular folds (plicae circulares)  Transverse ridges of mucosa and submucosa  Villi  Finger-like projections of the mucosa  Covered with simple columnar epithelium  Microvilli  Further increase surface area for absorption

36. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Histology of the Intestinal Wall  Absorptive cells  Uptake digested nutrients  Goblet cells  Secrete mucus that lubricates chyme  Enteroendocrine cells  Secrete hormones  Intestinal crypts  Epithelial cells secrete intestinal juice

37. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Small Intestine – Structural Features Figure 22.21a–d

38. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Large Intestine  Digested residue contains few nutrients  Small amount of digestion by bacteria  Main functions  Absorb water and electrolytes  Mass peristaltic movements force feces toward the rectum

39. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Gross Anatomy of Large Intestine  Subdivided into  Cecum, vermiform appendix, colon, rectum, anal canal  Special features of large intestine  Teniae coli  Thickening of longitudinal muscularis  Haustra  Puckering created by teniae coli  Epiploic appendages  Fat-filled pouches of visceral peritoneum

40. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Gross Anatomy of Large Intestine  Cecum  Blind pouch  Beginning of large intestine  Vermiform appendix  Contains lymphoid tissue  Neutralizes pathogens  Colon  Divided into distinct segments  Ascending, transverse, descending, and sigmoid colon

41. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Gross Anatomy of Large Intestine  Rectum  Descends along the inferior half of the sacrum  Anal Canal  The last subdivision of the large intestine  Lined with stratified squamous epithelium

42. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Gross Anatomy of Large Intestine Figure 22.22a

43. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Gross Anatomy of Large Intestine Figure 22.22b

44. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Vessels and Nerves of the Large Intestine  First half of large intestine  Arterial supply - superior mesenteric artery  Innervation  Sympathetic innervation – superior mesenteric and celiac ganglia  Parasympathetic innervation – vagus nerve

45. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Vessels and Nerves of the Large Intestine  Distal half of large intestine  Arterial supply - inferior mesenteric artery  Innervation  Sympathetic innervation – inferior mesenteric and hypogastric plexuses  Parasympathetic innervation – pelvic splanchnic nerves

46. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Defecation Reflex Figure 22.23

47. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Microscopic Anatomy of Large Intestine  Villi are absent  Contains numerous goblet cells  Intestinal crypts – simple tubular glands  Lined with simple columnar epithelial tissue  Epithelium changes at anal canal  Becomes stratified squamous epithelium

48. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Mucosa of the Large Intestine Figure 22.24

49. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Liver  Largest gland in the body  Performs over 500 functions  Digestive function  Bile production  Performs many metabolic functions

50. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Visceral Surface of the Liver Figure 22.26

51. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Microscopic Anatomy of the Liver  Hepatocyte – functional cells of the liver  Portal triad composed of  Bile duct tributary  Branch of hepatic portal vein  Branch of hepatic artery  Kupffer cells – destroy bacteria

52. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Microscopic Anatomy of the Liver  Some functions of hepatocytes  Rough ER manufactures blood proteins  Smooth ER produces bile salts, detoxifies poisons  Peroxisomes detoxify poisons (alcohol)  Golgi apparatus packages secretory products  Mitochondria provide energy for liver processes  Glycosomes store sugar  Great capacity for regeneration

53. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Microscopic Anatomy of Liver Figure 22.27a, c, d

54. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Gallbladder  Stores and concentrates bile  Expels bile into duodenum  Bile emulsifies fats  Cholecystokinin – released from enteroendocrine cells in response to fatty chyme

55. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Gallbladder Figure 22.20

56. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Pancreas  Exocrine function  Acinar cells make, store, and secrete pancreatic enzymes  Enzymes are activated in the duodenum  Endocrine function  Produces insulin and glucagon  Regulates blood sugar

57. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Exocrine Pancreas: Histology Figure 22.29a, b

58. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Disorders of the Digestive System  Intestinal obstruction  Mechanical obstructions  Adhesions, tumors, or foreign objects  Nonmechanical obstruction  Halt in peristalsis  Trauma  Intestines touched during surgery

59. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Disorders of the Digestive System  Inflammatory bowel disease  Inflammation of intestinal wall  Crohn’s disease  Ulcerative colitis  Viral hepatitis  Jaundice and flu-like symptoms  Major types – A, B, C, and G

60. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Disorders of the Digestive System  Cystic Fibrosis and the Pancreas  Pancreatic ducts become blocked with mucus  Clogged ducts prevent pancreatic juices from entering small intestine  Leads to malabsorption of fats and other nutrients

61. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Development of the Digestive System  Alimentary canal formed in week three  Encloses tubular portion of yolk sac  Vitelline duct  Landmark dividing into three regions  Forgut  Midgut  Hindgut