3. FUNCTIONS
• A. ingestion of food
• B. digestion; breaking down into smaller units
• C. absorption ; absorption of digested materials
4. overview
DIVISION;
A. ORAL CAVITY;
Food is cut into smaller pieces; moisten and initially digested.
Bolus of food is introduced to the alimentary canal
B. MUSCULAR ALIMENTARY CANAL
Food is converted to physically and chemically absorbable substance.
C. EXTRAMURAL GLANDULAR PORTION
6. MUCOSA
• A. epithelial surface
• B. lamina propia
• Composed of loose connective tissue, blood vessels, and lymph vessels, and sometimes lymphoid
tissues and glands
• Contain antibody producing cells ( lymphoid tissues ) sp. The immunoglobulin A or Ig A
• C. muscularis mucosa
• Smooth muscles
7. FUNCTIONS OF EPITHELIAL LINING OF GIT
• 1. selective barrier
• 2. facilitate transport and digestion of food
• 3. promote absorption of digestion of food
• 4. produce hormones necessary for the digestive activity
• 5. produce mucus for lubrication and protection
8. MUSCULARIS MUCOSA
• Movements is independent with other movements of the digestive tract, which
increase contraction
• Propels and mix food
9. SUBMUCOSA
• Composed of dense connective tissues, blood and lymph vessels
• It may also contain some lymphoid tissues and glands
• Contain nerve plexus called “ Meissner’s plexus “
10. TUNICA MUSCULARIS
• Two layers of smooth muscles
• A. inner circular
• B. outer longitudinal
• * plexus; myenteric plexus or Auerbach’s nerve plexus
• * blood and lymph vessels
11. SEROSA AND ADVENTITIA
a. serosa; outermost layer of the alimentary canal lined by simple squamous
epithelium called mesothelium.
peritoneum lines the wall of the cavity
both are rich with blood and lymph vessels. And also consist of adipose tissue
b. Adventitia; outermost layer replacing the adventitia in organs bound to another
organ. It is also composed of connective tissues with blood vessels. But
there is no mesothelium
15. ESOPHAGEAL GLANDS
located at the submucosal layer
secretion ; facilitates transport of food
and protects the mucosa
ESOPHAGEAL-CARDIAC GLANDS
located at the lamina propia of the
esophagus, at the junction of the esophagus
and cardia of the stomach
16. ESOPHAGUS ( MUSCULAR LAYER )
• A. distal end
• Located near the stomach
• Composed of smooth muscles and
• Form the lower esophageal sphincter
• B. mid portion
• Composed of mix skeletal & smooth muscle
• C. proximal end
• Composed of skeletal muscle only
18. STOMACH
• Dilated portion of the digestive system
• Functions;
• 1. continue digestion of carbohydrates
• 2. add acidic fluid to digested food forming chime
• 3. promote initial digestion of protein by secreting pepsin
19. Gross feature
4 regions;
a. Cardia
b. Fundus
c. Body
d. Pylorus
Wall; rugae
3 layers;
1. Inner oblique
2. Middle circular
3. Outer longitudinal
20. Layers
a. Mucosa
lined by simple columnar
invaginations are called gastric pits
Muscularis mucosae separates the mucosa
from the submucosa
21.
22. GASTRIC PITS
• LINING EPITHELIUM; simple columnar epithelium
• Importance; secretes alkaline mucus
• Components of mucus; water, lipids and glycoprotein
• Form a hydrophobic protective gel
23. FUNDUS AND THE BODY OF THE STOMACH
• Specifically located at the lamina propia ; gastric glands
• three distinct regions of each gastric glands;
• A. isthmus
• B. neck
• C. base
24. . .
• .
• The distribution of epithelial cells in gastric
glands is not uniform .
• 1) The isthmus, close to the gastric pit,
contains differentiating mucous cells that will
migrate and replace superficial mucous
cells, undifferentiated stem cells, and oxyntic
(parietal) cells;
• 2) the neck of the glands consists of stem,
mucous neck (different from the mucous
cells in the isthmus), and parietal cells;
• 3) the base of the glands primarily contains
parietal and chief (zymogenic) cells.
• Enteroendocrine cells are dispersed in the
neck and base of the glands.
Enteroendocrine cells are scattered at the
areas of the neck & base
25. Oxyntic or parietal cells
Secretes HCL, traces of electrolytes
and intrinsic factors
Eosinophilic cytoplasm and centrally located
nucleus
26. Chief cells or zymogenic cells
Basophilic cytoplasm
Secretes pepsinogen and lipase
27. Mucous neck cells
Present in clusters or single in between parietal cells
Secretes mucus different from mucus of the surface epithelium
28. Enteroendocrine cells
Found on the neck and base of the glands
Secretes serotonin at the fundus of the stomach
Enteroendocrine cells at the pylorus secretes somatostatin which
inhibits release of gastrin
Pyloric glands; secretes mucus and lysosomes
• Secretion of somatostatin is stimulated by HCL and counter
Balance acidity
30. • Submucosa
• Composed of dense connective tissue, blood and lymphatic vessels
• Infiltrated by lymphoid cells, macrophages and mast cells
• Muscularis
• 3 layers; inner oblique, middle circular and outer longitudinal
• At the middle layer , it is thickened to form the pyloric sphincter
• Serosa
• Covered by thin serosa
33. FUNCTIONS
• A. site of final digestion of food
• B. absorption of nutrients
• C. endocrine secretion
34. SMALL INTESTINE GENERALITIES
• A. Mucous membrane
• Folds are called “ plica circularis “ of Kerckring’s valve ( mucosa & submucosa )
• More prominent in jejunum
35.
36.
37. Crypts of Lieberkhun
Small opening of tubular glands in between villi
Contain stem cells, goblet cells, paneth’s cells and Enteroendocrine cells
38.
39. Absorptive cells or enterocytes
Columnar cells
Basal portion; nucleus
Apical portion; striated or brush border
42. Paneth’s cell
Exocrine gland found at the basal portion of the intestinal
Glands
contain granules with lysosomes, which play a role in
Controlling intestinal flora
43. Peyer’s patches
Found in the lamina propia
Contain lymphocytes and macrophages
Play a role in immunologic response
44. Lamina propia
Made up of loose connective tissue with blood and lymph vessels
Also contain nerves and smooth muscle cells
45. duodenum
Located at the submucosal
layer are duodenal glands
or brunner’s glands
Function; protects the gastric
mucosa from acidic gastric
juice
