Lecture 7: Histology of the Esophagus and Stomach Flashcards
What is the innermost layer of the digestive tube and what are its layers?
Mucosa:
Epithelium
Lamina propria
Muscularis mucosae
What’s found in the lamina propria?
- CT
- Lymphatic nodules and immunocompetent cells
- Glands and components of the circulatory system
What is the function of the Submucosa; houses glands in what 2 regions?
- Provides nerve, vascular, and lymphatics supply
- Houses glands in 2 regions: Esophagus and Duodenum
What 2 layers are found within the Muscularis Externa?
1) Inner circular layer of smooth muscle
2) Outer longitudinal layer of smooth muscle
What is the outermost layer composed of and where does it differ?
- Serosa in intraperitoneal structures
- Adventitia in retroperitoneal structures
Label the 7 arrows from top to bottom
1) Epithelium
2) Lamina propria
3) Muscularis Mucosa
4) Submucosa
5) Inner circular layer
6) Outer longitudinal layer
7) Serosa
Spinal levels of the: Greater, Lesser, Least, and Lumbar splanchinic nerves?
- Greater = T5-T9
- Lesser = T10-T11
- Least = T12
- Lumbar = L1-L2
Describe the path of the sympathetic branches of the nerves innervating the GI?
Presynaptic nerves which synapse in prevertebral ganglia (celiac, SMG, IMG, aorticorenal), the postsynaptic nerves then travel to organs via blood vessels
What are the 2 parasympathetic nerves for autonomic innervation of the GI; where do they stop and start?
1) Vagus nerve (stops at left colic flexure)
2) Pelvic splanchnics (left colic flexure inferiorly)
Pelvic splanchnics arise from what vertebral levels?
S2, S3, and S4
What are the intrinsic/enteric components of the GI tract innervation?
1) Submucosal plexus of Meissner (in submucosa)
2) Myenteric plexus of Auerbach
Where is the Myenteric plexus of Auerbach located?
Between the inner circular and outer longitudinal layers of the muscularis externa
What is denoted by ‘G’ in this picture?
Submucosal plexus of Meissner
What is denoted by the letter ‘G’ in this picture?
Myenteric plexus of Auerbach
What is the structure that the midde arrow is pointing to?
Myenteric plexus of Auerbach
What does sympathetic vs parasympathetic innervation do to gut motility?
Sympathetic = decreased motility
Parasympathetic = increased motility and secretions
What does the intrinsic/enteric component of the GI do?
- Peristaltic contractions of the ME and movements of muscularis mucosae
- Secretory activities of the muscosal and submucosal glands
What is the best way to identify the different regions of the esophagus, how so?
- Using the Muscularis Externa
Upper 1/3: both layers are striated muscle
Middle 1/3: smooth muscle seen deep to striated
Lower 1/3: both layers are smooth muscle
How do you know when you’re looking at the esophageal junction?
Epithelium changes from stratified squamous (esophagus) to simple columnar (stomach)
What is the arrow pointing at?
Gastro-esophageal junction
What is GERD, caused by?
Reflex of acidic contents into the esophagus, irritating the esophageal mucosa
What is this called clinically, caused by?
- Barret Esophagus
- Chronic GERD
- Stratified squamous epithelium replaced by metaplastic columnar epithelium
The normal transition from esophageal stratified squamous epithelium to gastric simple columnar epithelium occrs at which line?
Z-line
Label A-C on the stomach
A) Cardia
B) Fundus
C) Pyloric antrum
What are the folds of mucosa inside the stomach referred to as?
Rugae
What is found within the submucosa of the stomach?
- No glands
- Vascular plexus and the submucosal (Meissner’s) plexus
What is found within the Muscularis Externa of the stomach?
- Inner oblique
- Middle circular = pyloric sphincter and Myenteric plexus of Auerbach’s
- Outer longitudinal
What organ is this?
Stomach
What organ is this?
Stomach
What is found in the lamina propria of the body and fundus of the stomach?
Numerous gastric glands, BV’s, CT, and lymphoid cells
What is found within the lamina propria of the cardia of the stomach?
- Glands tubular (coiled) and continous w/ gastric pits
- Mucus-secreting cells predominate
- Parietal and chief cells present, but sparse
What is the lamina propria of the Pyloric region of stomach like?
- Deeper gastric pits
- Glands are larger lumen and highly branched
- Enteroendocrine cell, gastin-secreting G cells are abundant
What part of the stomach is this and how can you tell?
- Cardia mucosa
- Short pits and coiled glands
What part of the stomach is this and how can you tell?
- Body mucosa
- Short pits w/ long tubular glands
What part of the stomach is this and how can you tell?
- Pyloric mucosa
- Deep pits and highly branched w/ lympoid follicles
What cell type is pictured here?
Surface Mucous cells
What cell types are pictured here from left to right on the bottom arrows?
Left = parietal cells
Right = mucous neck cells
What are the cells denoted by A and B
A) Parietal cells
B) Chief Cells
What is the function of Parietal cells?
Secrete HCL and Intrinsic Factor (B12)
*Large oval cells, stain light pink
What is the function of Chief Cells?
- Contain zymogen granules
- Make pepsinogen
* Stain darker/bluish
What are the two types of cells denoted by the top and bottom blue boxes?
Top: Chief Cell
Bottom: Parietal Cell
What do Gastroenteroendocrine Cells produce?
- Somatostatin (D-cells)
- Gastrin (G-cells)
- Histamine (Enterochromaffin-like cells)
- Serotonin (Enterochromaffin cells)
- Ghrenlin (P/D(1)-type endocrine cells)
Which part of the Esophagus is this?
Middle 1/3
*Notice the smooth muscle AND striated muscle
What layer forms the pyloric sphincter?
Middle circular layer of the muscularis externa
What are the main cell types found in the Pylorus of the stomach?
- Mucus-secreting
- Enteroendocrine cells
- Gastrin-secreting G-cells
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