1. Chapter 19
The Digestive System

2. Key Terms absorption esophagus pancreas bile gallbladder peptic ulcer
chyle hydrolysis peristalsis
chyme ingestion peritoneum
defecation intestine saliva
deglutition lacteal sphincter
digestion liver stomach
duodenum mastication villi
emulsify mesentery

3. General Structure and Function of the Digestive System
General Functions
Digestion
Absorption
Elimination
Divisions
Digestive tract
Accessory organs

4. Figure 19-1 The digestive system.
Which accessory organs of digestion secrete into the mouth?

5. General Structure and Function of the Digestive System (cont.)
Peritoneum
Lines the abdominopelvic cavity; covers abdominal organs
Layers of the peritoneum
Parietal
Visceral
Subdivisions
Mesentery
Mesocolon
Greater omentum
Lesser omentum

6. General Structure and Function of the Digestive System (cont.)
The Wall of the Digestive Tract
Mucosal membrane, or mucosa
Submucosa
Smooth muscle, the muscularis externa
Serous membrane, or serosa

7. Figure 19-3 Wall of the digestive tract.
What type of tissue is between the submucosa and the serous membrane in the digestive tract wall?

8. General Structure and Function of the Digestive System (cont.)?
Pop Quiz 19.1 Which of the following is the correct order from the outermost to innermost layer? A) Submucosa, serous membrane, smooth muscle, mucous membrane B) Smooth muscle, serous membrane, mucous membrane, submucosa C) Serous membrane, smooth muscle, submucosa, mucosa D) Mucous membrane, submucosa, smooth muscle, serous membrane

9. General Structure and Function of the Digestive System (cont.)?
Pop Quiz Answer 19.1 Which of the following is the correct order from the outermost to innermost layer? A) Submucosa, serous membrane, smooth muscle, mucous membrane B) Smooth muscle, serous membrane, mucous membrane, submucosa C) Serous membrane, smooth muscle, submucosa, mucosa D) Mucous membrane, submucosa, smooth muscle, serous membrane

10. Organs of the Digestive Tract (cont.)
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine

11. Organs of the Digestive Tract (cont.)
The Mouth
Also called oral cavity, processes food by:
Ingestion
Mastication
Mixing with saliva
Deglutition
Tongue

12. Figure 19-4 Gastrointestinal motility.
Which type of motility would be most useful in the esophagus, where the contents should move quickly? 12

13. Organs of the Digestive Tract (cont.)
The Teeth
Sets of teeth
Deciduous
Permanent
Types of teeth
Incisors
Cuspids
Molars
Six-year molars
Premolars
Third molars or wisdom teeth

14. Organs of the Digestive Tract (cont.)
The Teeth (cont.)
Parts of a tooth
Dentin
Crown
Enamel
Root
The gum
Gingiva

15. Figure 19-5 The mouth and teeth.15

16. 16

17. Organs of the Digestive Tract (cont.)
The Pharynx
Also called the throat
Divisions
Oropharynx
Nasopharynx
Laryngopharynx
Soft palate
Uvula

18. Organs of the Digestive Tract (cont.)
The Esophagus
Muscular tube.
Food is lubricated with mucus.
Peristalsis.
No digestion occurs here.
Passes through esophageal hiatus of the diaphragm to join stomach.

19. Organs of the Digestive Tract (cont.)
The Stomach
Structure
Greater curvature
Lesser curvature
Fundus
Body
Pylorus
Sphincters
Lower esophageal sphincter (LES)
Pyloric

20. Organs of the Digestive Tract (cont.)
The Stomach (cont.)
Functions
Storage pouch
Rugae
Secrete substances to form gastric juice
Hydrochloric acid prepares proteins for digestion.
Pepsin digests proteins.
Delivery of chyme to the small intestine

21. Organs of the Digestive Tract (cont.)
The Small Intestine
Subdivisions of the small intestine
Duodenum
Jejunum
Ileum
Functions of the small intestine
Secretion
Motility
Digestion
Absorption

22. Figure 19-7 The intestines.22

23. Organs of the Digestive Tract (cont.)
The Large Intestine
Subdivisions of the large intestine
Cecum
Ileocecal valve
Appendix
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum
Anal canal
Anus

24. Organs of the Digestive Tract (cont.)
Functions of the large intestine
Production of mucus
Reabsorb some water
Form feces (stool)
Defecation

25. Organs of the Digestive Tract (cont.)?
Pop Quiz 19.2 Which organ receives food flowing through the pyloric sphincter? A) Stomach B) Jejunum C) Duodenum D) Esophagus

26. Organs of the Digestive Tract (cont.)?
Pop Quiz Answer 19.2 Which organ receives food flowing through the pyloric sphincter? A) Stomach B) Jejunum C) Duodenum D) Esophagus

27. The Accessory Organs (cont.)
Release secretions through ducts into the digestive tract.
Salivary glands open to mouth.
Other organs release secretions into the duodenum:
Liver
Gallbladder
Pancreas

28. The Accessory Organs (cont.)
Salivary Glands
Functions -Secrete saliva
Moistens food
Facilitates mastication and deglutition
Helps keep teeth and mouth clean
Three pairs:
Parotid glands
Submandibular glands
Sublingual glands

29. The Accessory Organs (cont.)
The Liver
Structure of the liver
Largest accessory organ
Right, left lobes
Portal vein
Hepatic artery

30. The Accessory Organs (cont.)
The Liver (cont.)
Functions of the liver
Manufactures bile
Controls blood glucose levels
Modifies fats
Stores some vitamins, iron
Forms blood plasma proteins
Destroys old red blood cells
Synthesizes urea
Detoxifies harmful substances

31. The Accessory Organs (cont.)
The Liver (cont.)
Bile
Manufactured in the liver.
Bile leaves the liver by ducts.
Common hepatic duct
Cystic duct
Common bile duct

32. Figure 19-9 Accessory organs of digestion.
Into which part of the small intestine do these accessory organs secrete? 32

33. The Accessory Organs (cont.)
The Gallbladder
Muscular sac
Located on inferior surface of the liver
Stores bile

34. The Accessory Organs (cont.)
The Pancreas
Gland that produces enzymes
Releases large amounts of sodium bicarbonate (NaHCO3)
Also functions as an endocrine gland

35. Enzymes and the Digestive Process (cont.)
Fundamental chemical process of digestion
Enzymes
Required for digestion
Catalysts
Highly specific proteins

36. 36

37. Enzymes and the Digestive Process (cont.)
Role of Water
Hydrolysis
Seven liters of water secreted into the digestive tract daily
Produces digestive juices
Dilutes food
Used in the chemical process of digestion

38. Figure Hydrolysis. 38

39. Digestion, Step by Step Digestion in the Mouth
Chews food, mixes with saliva
Some starches changed to sugars via salivary amylase
Digestion in the Stomach
Secretes HCl, enzymes
Denatures proteins
Secretes mucus
Forms chyme

40. Digestion, Step by Step (cont.)
Digestion in the Small Intestine
Most digestion occurs in the duodenum.
Fats
Carbohydrates
Proteins
Nucleic acids

41. Absorption (cont.) Villi in mucosa of the small intestine:
Arteriole and venule bridged with capillaries
Capillaries absorb:
Simple sugars
Small proteins
Amino acids
Simple fatty acids
Water
Portal system transports nutrients to the liver.

42. Absorption (cont.) Absorption of fats Lacteals absorb fat.
Fat/lymph mixture (chyle) drains from the small intestine.
Chyle merges with lymphatic circulation, enters blood in veins near the heart.
The liver further processes absorbed fats.

43. Absorption (cont.) Absorption of vitamins and minerals
Vitamins and minerals are absorbed from the small intestine.
Minerals and some vitamins mix with water and are absorbed directly into the blood.
Other vitamins are incorporated in fats and absorbed along with fats.
Vitamin K and some B vitamins are produced by bacterial action in the colon and are absorbed from the large intestine.

44. Figure 19-11 Carbohydrates.
Name the two monosaccharide components of sucrose. 44

45. Enzymes and the Digestive Process (cont.)?
Pop Quiz 19.3 Which enzyme digests carbohydrates? A) Amylase B) Pepsin C) Lipase D) Trypsin

46. Enzymes and the Digestive Process (cont.)?
Pop Quiz Answer 19.3 Which enzyme digests carbohydrates? A) Amylase B) Pepsin C) Lipase D) Trypsin

47. Control of Digestion and Eating (cont.)
Two types of control over digestion—nervous and hormonal
Nervous control of digestion
Parasympathetic stimulation increases activity
Sympathetic stimulation decreases activity
Hormonal control of digestion
Digestive organs produce hormones
Gastrin
Gastric inhibitory peptide (GIP)
Secretin
Cholecystokinin (CCK)

48. Control of Digestion and Eating (cont.)
Control of Hunger and Appetite
Hunger
Desire for food
Regulated by hypothalamic centers
Respond to nutrient levels
Satisfied by adequate meal
Appetite
No relationship to need for food
May not be satisfied by adequate meal

49. Control of Digestion and Eating (cont.)
Short-term regulation of hunger
Hypothalamus induces hunger sensations
Ghrelin hormone
Food consumption
Long-term regulation of body weight
Leptin hormone produced by adipocytes

50. Figure 19-12 Regulation of food intake.50

51. Control of Digestion and Eating (cont.)?
Pop Quiz 19.4 Which portion of the autonomic nervous system inhibits digestion? A) Somatic B) Parasympathetic C) Sympathetic D) Visceral

52. Control of Digestion and Eating (cont.)?
Pop Quiz Answer 19.4 Which portion of the autonomic nervous system inhibits digestion? A) Somatic B) Parasympathetic C) Sympathetic D) Visceral

53. Disorders of the Digestive System (cont.)
Peritonitis
Inflammation of the peritoneum following infection of an organ covered by peritoneum
Localized
Generalized
Examples of causative factors: ruptured appendix, perforated ulcer, penetrating wound

54. Disorders of the Digestive System (cont.)
Diseases of the Mouth and Teeth
Dental caries
Gingivitis
Periodontitis
Vincent disease
Oral thrush
Parotitis

55. Disorders of the Digestive System (cont.)
Disorders of the Esophagus and Stomach
Hiatal hernia and gastric reflux
Heartburn
Chronic reflux or gastroesophageal reflux disease (GERD)
Nausea and vomiting (emesis)
Stomach cancer
Gastritis and peptic ulcer
Pyloric stenosis

56. Figure 19-13 Disorders involving the esophagus and stomach.56

57. 57

58. Disorders of the Digestive System (cont.)
Intestinal Disorders
Inflammatory disorders
Appendicitis
Inflammatory bowel disease
Crohn disease
Ulcerative colitis
Celiac disease
Irritable bowel syndrome (IBS)
Enteritis and gastroenteritis
Diverticulitis

59. 59

60. Disorders of the Digestive System (cont.)
Intestinal Disorders (cont.)
Diarrhea
Constipation
Spastic constipation
Flaccid constipation
Intestinal obstruction
Intussusception
Volvulus
Colon and rectal cancer
Sigmoidoscope
Colonoscope

61. Figure 19-14 Intestinal obstructions.61

62. Figure 19-15 Imaging of the colon.62

63. Disorders of the Digestive System (cont.)
Cirrhosis and Other Liver Diseases
Cirrhosis
Active liver cells replaced by inactive connective (scar) tissue.
Alcoholic (portal) cirrhosis is most common type.
Varicose veins (varices) of the digestive tract.
Jaundice
Hepatitis
Types of hepatitis virus: A, B, C, D, E
Liver cancer

64. 64

65. Disorders of the Digestive System (cont.)
Gallstones
Cholelithiasis
Cholecystitis
Pancreatic Disorders
Pancreatitis
Pancreatic cancer

66. Figure Gallstones. 66

67. 67

68. Effects of Aging and the Digestive System
Decreased digestive organ activity
Decrease in saliva
Tooth loss
Poor nutrient absorption
Slowing of peristalsis
Decreased tissue replacement
Increased risk of cancer

69. Case Study Learning Objective
16. Using the case study, describe the colonoscopy procedure and its role in diagnosing certain colon disorders. 69

70. Case Study (cont.) Colonoscopy
Recommended for people over the age of 50 years as baseline; every 10 years thereafter for low-risk persons
Used to detect colorectal cancers
Preparation:
Nothing to eat from the evening prior to the examination
Bowel cleansing
Types of colonoscopies:
Flexible lighted endoscope
Virtual colonoscopy using computerized x-rays
May remove polyps and abnormal tissue with endoscope 70

71. Word Anatomy (cont.) Word Part Meaning Example
General Structure and Function of the Digestive System
ab-
away from
In absorption, digested materials are taken from the digestive tract into the circulation.
enter/o
intestine
The mesentery is the portion of the peritoneum around the intestine.
mes/o-
middle
The mesocolon, like the mesentery, comes from the middle layer of cells in the embryo, the mesoderm.
Organs of the Digestive Tract
gastr/o
stomach
The gastrointestinal tract consists mainly of the stomach and intestine.

72. Word Anatomy (cont.) Word Part Meaning Example The Accessory Organs
amyl/o
starch
The starch-digesting enzyme in saliva is salivary amylase.
bil/i
bile
Bilirubin is a pigment found in bile.
cyst/o
bladder, sac
The cystic duct carries bile into and out of the gallbladder.
hepat/o
liver
The hepatic portal system carries blood to the liver.
lingu/o
tongue
The sublingual salivary glands are under the tongue.
Control of Digestion
chole-
bile, gall
Cholecystokinin is a hormone that activates the gallbladder (cholecyst/o).

73. Word Anatomy (cont.) Word Part Meaning Example
Disorders of the Digestive System
lith-
stone
A fecalith is a hardened piece of fecal material.
odont/o
tooth
Periodontitis is a disease of the gums and the tissue around a tooth.
-rhea (the “r” is doubled when added to a word)
flow, discharge
Diarrhea is a flow of watery bowel movements through (dia-) the digestive tract.