1. Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Seventh Edition Elaine N. Marieb Chapter 14 The Digestive System and Body Metabolism

2. The Digestive System and Body Metabolism Slide 14.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Digestion  Breakdown of ingested food  Absorption  Passage of nutrients into the blood  Metabolism  Production of cellular energy (ATP)

3. Organs of the Digestive System Slide 14.2a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Two main groups  Alimentary canal – continuous coiled hollow tube  Accessory digestive organs

4. Organs of the Digestive System Slide 14.2b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.1

5. Organs of the Alimentary Canal Slide 14.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Mouth  Pharynx  Esophagus  Stomach  Small intestine  Large intestine  Anus

6. Mouth (Oral Cavity) Anatomy Slide 14.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Lips (labia) – protect the anterior opening  Cheeks – form the lateral walls  Hard palate – forms the anterior roof  Soft palate – forms the posterior roof  Uvula – fleshy projection of the soft palate Figure 14.2a

7. Mouth (Oral Cavity) Anatomy Slide 14.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Vestibule – space between lips externally and teeth and gums internally  Oral cavity – area contained by the teeth  Tongue – attached at hyoid and styloid processes of the skull, and by the lingual frenulum Figure 14.2a

8. Mouth (Oral Cavity) Anatomy Slide 14.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Tonsils  Palatine tonsils  Lingual tonsil Figure 14.2a

9. Processes of the Mouth Slide 14.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Mastication (chewing) of food  Mixing masticated food with saliva  Initiation of swallowing by the tongue  Allowing for the sense of taste

10. Pharynx Anatomy Slide 14.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Nasopharynx – not part of the digestive system  Oropharynx – posterior to oral cavity  Laryngopharynx – below the oropharynx and connected to the esophagus Figure 14.2a

11. Pharynx Function Slide 14.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Serves as a passageway for air and food  Food is propelled to the esophagus by two muscle layers  Longitudinal inner layer  Circular outer layer  Food movement is by alternating contractions of the muscle layers (peristalsis)

12. Esophagus Slide 14.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Runs from pharynx to stomach through the diaphragm  Conducts food by peristalsis (slow rhythmic squeezing)  Passageway for food only (respiratory system branches off after the pharynx)

13. Layers of Alimentary Canal Organs Slide 14.11a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Mucosa  Innermost layer  Moist membrane  Surface epithelium  Small amount of connective tissue (lamina propria)  Small smooth muscle layer

14. Layers of Alimentary Canal Organs Slide 14.11b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Submucosa  Just beneath the mucosa  Soft connective tissue with blood vessels, nerve endings, and lymphatics

15. Layers of Alimentary Canal Organs Slide 14.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Muscularis externa – smooth muscle  Inner circular layer  Outer longitudinal layer  Serosa  Outermost layer – visceral peritoneum  Layer of serous fluid-producing cells

16. Layers of Alimentary Canal Organs Slide 14.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.3

17. Stomach Anatomy Slide 14.15a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Located on the left side of the abdominal cavity  Food enters at the cardioesophageal sphincter

18. Stomach Anatomy Slide 14.15b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Regions of the stomach  Cardiac region – near the heart  Fundus  Body  Phylorus – funnel-shaped terminal end  Food empties into the small intestine at the pyloric sphincter

19. Stomach Anatomy Slide 14.16a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Rugae – internal folds of the mucosa  External regions  Lesser curvature  Greater curvature

20. Stomach Anatomy Slide 14.16b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Layers of peritoneum attached to the stomach  Lesser omentum – attaches the liver to the lesser curvature  Greater omentum – attaches the greater curvature to the posterior body wall  Contains fat to insulate, cushion, and protect abdominal organs

21. Stomach Anatomy Slide 14.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.4a

22. Stomach Functions Slide 14.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Acts as a storage tank for food  Site of food breakdown  Chemical breakdown of protein begins  Delivers chyme (processed food) to the small intestine

23. Specialized Mucosa of the Stomach Slide 14.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Simple columnar epithelium  Mucous neck cells – produce a sticky alkaline mucus  Gastric glands – secrete gastric juice  Chief cells – produce protein-digesting enzymes (pepsinogens)  Parietal cells – produce hydrochloric acid  Endocrine cells – produce gastrin

24. Structure of the Stomach Mucosa Slide 14.20a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Gastric pits formed by folded mucosa  Glands and specialized cells are in the gastric gland region

25. Structure of the Stomach Mucosa Slide 14.20b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.4b, c

26. Small Intestine Slide 14.21 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  The body’s major digestive organ  Site of nutrient absorption into the blood  Muscular tube extending form the pyloric sphincter to the ileocecal valve  Suspended from the posterior abdominal wall by the mesentery

27. Subdivisions of the Small Intestine “Dogs Just Itch! Slide 14.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Duodenum  Attached to the stomach  Curves around the head of the pancreas  Jejunum  Attaches anteriorly to the duodenum  Ileum  Extends from jejunum to large intestine

28. Chemical Digestion in the Small Intestine Slide 14.23a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Source of enzymes that are mixed with chyme  Intestinal cells  Pancreas  Bile enters from the gall bladder

29. Chemical Digestion in the Small Intestine Slide 14.23b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.6

30. Villi of the Small Intestine Slide 14.24 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Fingerlike structures formed by the mucosa  Give the small intestine more surface area Figure 14.7a

31. Microvilli of the Small Intestine Slide 14.25 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Small projections of the plasma membrane  Found on absorptive cells Figure 14.7c

32. Structures Involved in Absorption of Nutrients Slide 14.26 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Absorptive cells  Blood capillaries  Lacteals (specialized lymphatic capillaries) Figure 14.7b

33. Folds of the Small Intestine Slide 14.27 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Called circular folds or plicae circulares  Deep folds of the mucosa and submucosa  Do not disappear when filled with food  The submucosa has Peyer’s patches (collections of lymphatic tissue)

34. Digestion in the Small Intestine Slide 14.57a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Enzymes from the brush border  Break double sugars into simple sugars  Complete some protein digestion  Pancreatic enzymes play the major digestive function  Help complete digestion of starch (pancreatic amylase)  Carry out about half of all protein digestion (trypsin, etc.)

35. Digestion in the Small Intestine Slide 14.57b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Pancreatic enzymes play the major digestive function (continued)  Responsible for fat digestion (lipase)  Digest nucleic acids (nucleases)  Alkaline content neutralizes acidic chyme

36. Absorption in the Small Intestine Slide 14.59 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Water is absorbed along the length of the small intestine  End products of digestion  Most substances are absorbed by active transport through cell membranes  Lipids are absorbed by diffusion  Substances are transported to the liver by the hepatic portal vein or lymph

37. Propulsion in the Small Intestine Slide 14.60 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Peristalsis is the major means of moving food  Segmental movements  Mix chyme with digestive juices  Aid in propelling food

38. Large Intestine Slide 14.28 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Larger in diameter, but shorter than the small intestine  Frames the internal abdomen

39. Large Intestine Slide 14.28 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.8

40. Functions of the Large Intestine Slide 14.29 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Absorption of water  Eliminates indigestible food from the body as feces  Does not participate in digestion of food  Goblet cells produce mucus to act as a lubricant

41. Structures of the Large Intestine Slide 14.30a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Cecum – saclike first part of the large intestine  Appendix  Accumulation of lymphatic tissue that sometimes becomes inflamed (appendicitis)  Hangs from the cecum

42. Structures of the Large Intestine Slide 14.30b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Colon  Ascending  Transverse  Descending  S-shaped sigmoidal  Rectum  Anus – external body opening

43. Structures of the Large Intestine Slide 14.30b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Colon  Ascending  Transverse  Descending  S-shaped sigmoidal  Rectum  Anus – external body opening

44. Food Breakdown and Absorption in the Large Intestine Slide 14.61 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  No digestive enzymes are produced  Resident bacteria digest remaining nutrients  Produce some vitamin K and B  Release gases  Water and vitamins K and B are absorbed  Remaining materials are eliminated via feces

45. Propulsion in the Large Intestine Slide 14.62 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sluggish peristalsis  Mass movements  Slow, powerful movements  Occur three to four times per day  Presence of feces in the rectum causes a defecation reflex  Internal anal sphincter is relaxed  Defecation occurs with relaxation of the voluntary (external) anal sphincter

46. Accessory Digestive Organs Slide 14.32 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Salivary glands  Teeth  Pancreas  Liver  Gall bladder

47. Salivary Glands Slide 14.33 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Saliva-producing glands  Parotid glands – located anterior to ears  Submandibular glands  Sublingual glands

48. Saliva Slide 14.34 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Mixture of mucus and serous fluids  Helps to form a food bolus  Contains salivary amylase to begin starch digestion  Dissolves chemicals so they can be tasted

49. Teeth Slide 14.35a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  The role is to masticate (chew) food  Humans have two sets of teeth  Deciduous (baby or milk) teeth  20 teeth are fully formed by age two

50. Teeth Slide 14.35b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Permanent teeth  Replace deciduous teeth beginning between the ages of 6 to 12  A full set is 32 teeth, but some people do not have wisdom teeth

51. Classification of Teeth Slide 14.36a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Incisors  Canines  Premolars  Molars

52. Classification of Teeth Slide 14.36b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.9

53. Regions of a Tooth Slide 14.37a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Crown – exposed part  Outer enamel  Dentin  Pulp cavity  Neck  Region in contact with the gum  Connects crown to root Figure 14.10

54. Regions of a Tooth Slide 14.37b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Root  Periodontal membrane attached to the bone  Root canal carrying blood vessels and nerves Figure 14.10

55. Pancreas Slide 14.38 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Produces a wide spectrum of digestive enzymes that break down all categories of food  Enzymes are secreted into the duodenum  Alkaline fluid introduced with enzymes neutralizes acidic chyme  Endocrine products of pancreas  Insulin  Glucagons

56. Liver Slide 14.39 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Largest gland in the body  Located on the right side of the body under the diaphragm  Consists of four lobes suspended from the diaphragm and abdominal wall by the falciform ligament  Connected to the gall bladder via the common hepatic duct

57. Bile Slide 14.40 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Produced by cells in the liver  Composition  Bile salts  Bile pigment (mostly bilirubin from the breakdown of hemoglobin)  Cholesterol  Phospholipids  Electrolytes

58. Role of the Liver in Metabolism Slide 14.77 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Several roles in digestion  Detoxifies drugs and alcohol  Degrades hormones  Produce cholesterol, blood proteins (albumin and clotting proteins)  Plays a central role in metabolism

59. Gall Bladder Slide 14.41 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sac found in hollow fossa of liver  Stores bile from the liver by way of the cystic duct  Bile is introduced into the duodenum in the presence of fatty food  Gallstones can cause blockages

60. Processes of the Digestive System Slide 14.42a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Ingestion – getting food into the mouth  Propulsion – moving foods from one region of the digestive system to another

61. Processes of the Digestive System Slide 14.42b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Peristalsis – alternating waves of contraction  Segmentation – moving materials back and forth to aid in mixing Figure 14.12

62. Processes of the Digestive System Slide 14.43 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Mechanical digestion  Mixing of food in the mouth by the tongue  Churning of food in the stomach  Segmentation in the small intestine

63. Processes of the Digestive System Slide 14.44 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Chemical Digestion  Enzymes break down food molecules into their building blocks  Each major food group uses different enzymes  Carbohydrates are broken to simple sugars  Proteins are broken to amino acids  Fats are broken to fatty acids and alcohols

64. Processes of the Digestive System Slide 14.45 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Absorption  End products of digestion are absorbed in the blood or lymph  Food must enter mucosal cells and then into blood or lymph capillaries  Defecation  Elimination of indigestible substances as feces

65. Processes of the Digestive System Slide 14.46 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.11

66. Control of Digestive Activity Slide 14.47a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Mostly controlled by reflexes via the parasympathetic division  Chemical and mechanical receptors are located in organ walls that trigger reflexes

67. Control of Digestive Activity Slide 14.47b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Stimuli include:  Stretch of the organ  pH of the contents  Presence of breakdown products  Reflexes include:  Activation or inhibition of glandular secretions  Smooth muscle activity

68. Nutrition - Take a Class! Slide 14.63 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Nutrient – substance used by the body for growth, maintenance, and repair  Categories of nutrients  Carbohydrates: simple sugars, starches, fiber  Lipids: triglycerides, phospholipids, fatty acids  Proteins: amino acids  Vitamins  Mineral  Water

69. Body Energy Balance Slide 14.83 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Energy intake = total energy output (heat + work + energy storage)  Energy intake is liberated during food oxidation  Energy output  Heat is usually about 60%  Storage energy is in the form of fat or glycogen