Download fundic glands

HISTOLOGY OF THE UPPER GIT
Objectives
 By the end of this lecture, the student should
be able to discuss the microscopic structure in
correlation with the function of the following
organs:

1) Esophagus.

2) Stomach.
Alimentary Canal
 Is the tubular portion of digestive
system.
 Is subdivided into: esophagus,
stomach, small intestine (duodenum,
jejunum and ileum), and large
intestine (cecum, colon, rectum, anal
canal, and appendix).
General Architecture
of L/M Structure of Alimentary Canal
General Architecture
of L/M Structure of Alimentary
Canal
Serosa
ESOPHAGUS
Four concentric layers:
1. Mucosa:
 Epithelial Lining:
Non-Keratinized Str. Squamous Epith.
 Lamina propria: C.T. containing blood
vessels, nerves and lymphatic vessels
(Peyer’s patches)
 Muscularis mucosae:
Few layers of smooth muscle fibers.
Serosa
Esophagus
2.
Submucosa:
 Connective tissue containing blood
vessels, nerves, glands &
 Meissner’s plexus of nerve fibers and
nerve cells.
3. Muscularis Externa:
Usually 2 smooth muscle layers:
 Inner circular layer.
 Outer longitudinal layer.
 Auerbach’s (myenteric) plexus in
between the 2 layers
4. Serosa or adventitia:
Serosa is C.T. covered by mesothelium (simple
squamous epithelium) in the abdominal part
of the esophagus. or adventitia if there is no
mesothelium.
Serosa
STOMACH
 It has 4 regions: cardia,
fundus, body and
pylorus.
 Mucosa has folds,
known as rugae that
disappear in the
distended stomach.
fundus
cardia
body
pylorus
Fundus of Stomach
 Mucosa: modify to form fundic glands. The
surface epithelium is simple columnar
mucus-secreting cells.
 Submucosa:
 Connective tissue containing blood
vessels & nerves.
 NO glands.
 Muscularis Externa:
 Three smooth muscle layers:
 Inner oblique.
 Middle circular.
 Outer longitudinal.
 Serosa:
 C.T. covered by mesothelium.
Mucosa of Fundus of Stomach
 It is composed of:
1. Surface Epithelium.
2. Fundic glands.
3. Lamina propria: invaded by numerous fundic
glands.
4. Muscularis mucosae.
Fundic Glands
Fundic glands have:
• Short pits—one
fourth of mucosa.
• Simple or branched
tubular glands.
• Are rich in parietal &
chief cells.
Fundic Glands
Composed of 6 cell types:
1. Parietal cells: secrete HCl and
gastric intrinsic factor that
helps absorption of vitamin B12.
2. Peptic (chief) cells:
secrete pepsinogen.
3. Mucous neck cells:
secrete mucus.
4. Enteroendocrine (DNES) cells:
secrete hormones.
5. G cells : secrete gastrin
6. Stem cells: regenerative cells.
Parietal and Chief
Cells
1- Parietal cells
2- Chief cells
1
2
PYLORUS OF STOMACH
 Mucosa: modify to form pyloric
glands. The surface epithelium is
simple columnar mucus-secreting
cells.
 Submucosa:
 Connective tissue containing
blood vessels & nerves.
 NO glands.
 Muscularis Externa:
 Two smooth muscle layers:
 Inner circular.
 Outer longitudinal.
 Serosa:
 C.T. covered by mesothelium.
Pyloric glands
 Their pits are deep --- about half
the length of mucosa.
 They are branched and
convoluted --- many cross
sections.
 The predominant cells are
mucous neck cells that secrete
mucus.
Clinical Application
1. Hiatus Hernia
 Definition: It is herniation of the stomach into the
thoracic cage through a gap in the diaphragm
around the wall of the esophagus.
 Background: As the esophagus passes through the
diaphragm, it is reinforced by the muscle fibers of
the diaphragm. In some people, development is
abnormal, causing a gap in the diaphragm around
the wall of the esophagus.
Clinical Application
2. Barrett’s Syndrome
 Definition: It is probably a pre-cancerous (pre-
malignant) condition due to gastro-esophageal
reflux, leading to the replacement of part of the
stratified non-keratinized squamous epithelium of
the lowest region of the esophagus (at least 3 cm)
by a simple columnar epithelium (metaplasia).
 Treatment: Esophageal resection of the
metaplastic part.
Clinical Application
3. Gastric Intrinsic Factor
 Background: Gastric intrinsic factor (IF) is
secreted by parietal cells in gastric glands.
 It is necessary for vitamin B12 absorption from
the ileum.
 Effect of absence of gastric IF: it results in
deficiency of vitamin B12 with consequent
development of pernicious anemia.
Clinical Application
4. Atrophic Gastritis
 Effect of Atrophic Gastritis: Both parietal
and chief cells are much less numerous → the
gastric juice has little or no acid or pepsin
activity.
Clinical Application
5. Peptic Ulcer
 Definition: a circumscribed ulceration of the gastrointestinal mucosa extends to the submucosa and may
include the muscle layer, occurring in areas exposed to
acid and pepsin and most often caused by Helicobacter
pylori infection.
 NB: Gastric erosion: Damage of the gastro-intestinal
mucosa that is not penetrating the muscularis mucosae.
 Types of peptic ulcers:


Gastric peptic ulcer.
Duodenal peptic ulcer: especially in the 1st part of duodenum.
 Causes of peptic ulcer:
 Helicobacter Pylori (H. Pylori): this type of bacteria is
responsible for most of ulcers (70-90%)
 Non-steroidal anti-inflammatory drugs (NSAIDs): Long term
use of these pain relievers is the second most common cause
of ulcers e.g. Ibuprofen, aspirin
 Pathogenesis: Break-down of the thin protective layer
of mucus over the surface of epithelial cells leads to
damage of the gastric mucosa by the gastric acidity.
 Complications of peptic ulcer:
 Perforation of the wall of the stomach → peritonitis.
 Malignancy (in gastric peptic ulcer).
 Bleeding .
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The End ”
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