1. Chapter 24
The Digestive System

2. Functions of the Digestive System
Ingest food
Digest food
Absorb nutrients
Eliminate indigestible waste

3. Digestive anatomy overview

4. Organization of the Digestive organs
Alimentary Canal
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Accessory organs
Teeth
Tongue
Salivary glands
Gall bladder
Liver
Pancreas

5. The Digestive Process Ingestion Propulsion Mechanical Digestion
Chemical Digestion
Absorption
Defecation

6. Daddy, what does “retroperitoneal” mean?

7. This is your basic alimentary tract structure.

8. Sagittal view of abdominal viscera

9. Mesenteries
Figure 24–2a, b

10. Mesenteries
Figure 24–2c, d

11. Peristalsis
Figure 24–4

12. Segmentation Cycles of contraction: Does not follow a set pattern:
Churn and fragment bolus
mix contents with intestinal secretions
Does not follow a set pattern:
does not push materials in any 1 direction

13. The oral cavity and pharynx Say “ahhh”

14. Salivary Glands

15. Road map of the tongue

16. Anatomy of Teeth

17. Primary and Secondary Dentitions
Figure 24–9

18. Histology of the Esophagus

19. Gastroesophageal junction
Stomach
Esophagus
Stratified squamous epithelium
Simple columnar epithelium

20. The Swallowing Process
Figure 24–11

21. The Stomach
Figure 24–12a

22. The Stomach
Figure 24–12b

23. The Stomach Lining
Figure 24–13

24. It’s the pits! (Gastric pits that is…)

25. Micrograph of the Fundic region of the gastric mucosa

26. Secretion of HCl

27. Details of HCl secretion

28. The Regulation of Digestive Activities
Figure 24–5

29. Stimulus and control of gastric activity

30. The phases of gastric secretion

31. Control mechanisms of gastric contractions

32. The duodenum, gall bladder and pancreas

33. Hormonal Regulation of Pancreatic secretions

34. The small intestine

35. Histology of the small intestine

36. Cells of the mucosa

37. Duodenal wall

38. Duodenal mucosa

39. Brunner’s (duodenal) glands
You only find us here,
In the duodenum!
Brunner’s (duodenal) glands

40. Crypts of Lieberkuhn!
Paneth cells

41. Peyer’s patches in the ileum

42. The Pancreas
Figure 24–18

43. Exocrine tissues of the pancreas

44. Pancreas: Acinar cells

45. Activation of pancreatic proteases in the duodenum

46. Regulatory mechanisms for release of pancreatic juice

47. The Liver Is the largest visceral organ (1.5 kg)
Lies in right hypochondriac and epigastric regions
Extends to left hypochondriac and umbilical regions
Performs essential metabolic and synthetic functions

48. The Anatomy of the Liver
Figure 24–19

49. Liver Histology
Figure 24–20

50. 3 Functions of the Liver Metabolic regulation Hematological regulation
Bile production

51. Metabolic Regulation The liver regulates:
composition of circulating blood
nutrient metabolism
waste product removal
nutrient storage
drug inactivation

52. Metabolic Activities of the Liver
Carbohydrate metabolism
Lipid metabolism
Amino acid metabolism
Waste product removal
Vitamin storage
Mineral storage
Drug inactivation

53. The Gallbladder and Bile Ducts
Figure 24–21

54. The Gallbladder Stores bile Releases bile into duodenum:
only under stimulation of hormone cholecystokinin (CCK)

55. Gallstones Are crystals of insoluble minerals and salts
Form if bile is too concentrated
Small stones may be flushed through bile duct and excreted

56. Activities of Major Digestive Tract Hormones
Figure 24–22

57. Hormones of Duodenal Enteroendocrine Cells
Coordinate digestive functions:
secretin
cholecystokinin (CCK)
gastric inhibitory peptide (GIP)
vasoactive intestinal peptide (VIP)
gastrin
enterocrinin

58. Absorption of Nutrients
Nearly all occurs in the small intestine.
80% of the electrolytes and virtually all food
Most nutrients are absorbed by active transport.
Glucose, amino acids, & nucleic acids are absorbed by secondary active transport with sodium.
Iron and calcium require transport proteins (ferritin) or cofactors (vitamin D).
Anions follow Na+.
Vitamins -
Fat soluble (A, D, E & K) vitamins are carried with micelles. Much of the K is absorbed in the colon.
Water soluble vitamins diffuse with the exception of B12, which requires intrinsic factor.

59. Chemical Digestion & absorption of nutrients

60. Movement of absorbed nutrients

61. Chemical Digestion
Carbohydrates & proteins

62. Chemical Digestion
Lipids & Nucleic acids

63. Protein digestion in the small intestine

64. Bile salts emulsify fats

65. Absorption of lipid
Dietary fats are absorbed into the “lacteals” of the lymphatic system before being transferred to the circulatory system.

66. Digestive Secretion and Absorption
Figure 24–27

67. Absorption of Ions and Vitamins
Table 24–4

68. Lacteals

69. Anatomy of the large intestine

70. The rectum and anus

71. 3 Parts of the Large Intestine
Cecum:
the pouchlike first portion
Colon:
the largest portion
Rectum:
the last 15 cm of digestive tract

72. Histology of the colon

73. The Colon
Look at all those goblet cells!

74. Large intestine wall

75. Close-up of the colonic mucosa

76. Characteristics of the Colon
Lack of villi
Abundance of goblet cells
Presence distinctive intestinal glands

77. The Defecation reflex

78. Absorption of Nutrients: redux
Nearly all occurs in the small intestine.
80% of the electrolytes and virtually all food
Most nutrients are absorbed by active transport.
Glucose, amino acids, & nucleic acids are absorbed by secondary active transport with sodium.
Iron and calcium require transport proteins (ferritin) or cofactors (vitamin D).
Anions follow Na+.
Vitamins -
Fat soluble (A, D, E & K) vitamins are carried with micelles. Much of the K is absorbed in the colon.
Water soluble vitamins diffuse with the exception of B12, which requires intrinsic factor.

79. Summary: Chemical Events in Digestion
Figure 24–26

80. Clinical terms
Ascites – Fluid accumulation in the peritoneal cavity. Possible causes: hypertension, cirrhosis, renal or heart disease
Bulimia & anorexia nervosa – eating disorders
Cholecystitis – gallbladder inflammation. Can be caused by gallstones.
Diverticuliosis/diverticulitis – herniations of the colon wall which may become inflammed.
Dysphagia – difficulty swallowing.
GERD – Gastroesophogeal reflux disease. Excess acid and/or dyfunction of the gastroesophogeal sphincter.
IBS – inflammatory bowel syndrome. Related to Crohn’s disease or ulcerative colitis.
Pancreatitis – inflammation of the pancreas. Pancreatic enzymes activated in the within the duct. Can be caused by excessive dietary fats hyperstimulating the pancreatic secretion.
Peptic ulcers – usually caused by Helicobacter pylori.

81. Helicobacter pylori

82. Worldwide Distribution of H. pylori

83. Next, Energy Metabolism
The End
Next, Energy Metabolism