1. I. General Description and Considerations
Digestive System
I. General Description and Considerations

2. A. Paradox of similarity and change
All organs of the GI tract are modifications of a simple tube
Epithelium of the entire tract is derived from a single embryonic germ cell layer
All organs have some function related to digestion
All areas of the tract have basically the same histological layers

3. A. Paradox of similarity and change
However,
Abrupt changes occur in the epithelium from one organ to the next
Drastic modifications of the mucosa occur from one organ to the next
Each organ along the tract performs a separate and unique function related to digestion

4. B. General description Mucosa Submucosa Muscularis externa Adventitia
Epithelium
Lamina propria
Muscularis mucosa
Submucosa
Muscularis externa
Adventitia

5. General Plan of the GI Tract

6. Digestive System
II. Esophagus

7. A. General description and functions
Length, location, & relationships
Innervation
Functions

8. II. Esophagus
General
Mucosa
Submucosa
Muscularis
Adventitia

9. B. Mucosa Non-keratinized stratified squamous epithelium
Lamina propria
Muscularis mucosa

10. C. Submucosa
Contributes to large longitudinal folds of esophagus - these smooth out during swallowing

11. C. Submucosa
2. Contains esophageal glands - compound tubuloalveolar, mucus secreting

12. D. Muscularis externa Upper one-third Middle one-third Lower one-third
Innervation

13. E. Adventitia
Intrathoracic portion blends with surrounding dense irregular FECT
Below diaphragm covered with visceral peritoneum

14. Gastro-Esophageal Junction

15. Gastro-Esophageal Junction

16. Gastro-Esophageal Junction

17. Esophageal Ulcer

18. Digestive System
III. Stomach

19. A. General description & functions
Role in digestion and storage
4 gross anatomic vs. 3 histological divisions
Rugae

20. Stomach Regions & Glands

21. B. Mucosa
Surface
esophageal-gastric junction - abrupt change from stratified squamous to simple columnar
gastric pits - fine furrows, lead into glands
simple columnar epithelium - forms sheet gland, all mucus secreting, mucus has a basic pH

22. Gastric Lining Cells & Pits

23. B. Mucosa Gastric gland structure & nomenclature
simple, branched tubular glands - occupy entire thickness of mucosa
each gland has a neck, body, and base

24. B. Mucosa Gastric gland structure & nomenclature
simple, branched tubular glands - occupy entire thickness of mucosa
each gland has a neck, body, and base

25. B. Mucosa Lamina propria occupies space between glands and pits
richly vascularized and slips of smooth muscle from muscularis mucosa

26. B. Mucosa Cardiac glands
in cardiac region of stomach, near esophageal orifice
length of gland approximately equal to depth of pit
mostly mucus secreting cells with a few parietal and enteroendocrine cells
primary function is to produce a protective mucus secretion

27. B. Mucosa
Cardiac glands

28. B. Mucosa Fundic glands located in fundic and body regions of stomach
one or more open into each gastric pit, glands are much longer than their pits are deep
classified as simple branched tubular
closely packed, perpendicular to surface
major source of gastric juice

29. B. Mucosa
Fundic glands

30. B. Mucosa
Fundic gland cells
Mucus Neck
Parietal
Chief
Enteroendocrine

31. Fundic Stomach

32. Gastric Pits

33. Fundic Glands – Neck & Body

34. Parietal Cell

35. Fundic Glands - Base

36. Enteroendocrine Cells

37. Enteroendocrine Cell

38. B. Mucosa
7. Pyloric glands

39. Pyloric Stomach

41. Meisner’s Plexus

42. Muscularis Externa

43. Auerbach’s Plexus

46. Gastric Ulcer

48. Gastroduodenal Junction

49. Gastroduodenal Junction