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GIGU Exam 1 > Histology of the Esophagus & Stomach > Flashcards

Histology of the Esophagus & Stomach Flashcards

1
Q

What are the four layers of the GI tract from the lumen to superficial?

A
  1. Mucosa
  2. Submucosa
  3. Muscularis Externa
  4. Serosa/adventitia
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2
Q

What are the three layers of the mucosa and their function?

A

1) Lining epithelium: changes throughout GI tract
2) Lamina propria: lymph and immune cells
3) Muscularis mucosae: smooth muscle that controls mobility & infoldings of mucosa above it

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3
Q

What composes the submucosal layer?

A

Dense irregular connective tissue with neurovasculature and lymphatics. Glands may also be present (Esophagus & duodenum)

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4
Q

What are the two layers of the muscularis externa & their function?

A
  1. Inner circular layer - constricts lumen
  2. Outer longitudinal layer - shortens the tube

*neurovasculature plexus between layers

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5
Q

What is the difference between serosa and adventitia?

A

Serosa: connective tissue - mesothelial lining covering peritoneal organs

Adventitia: connective tissue - Retroperitoneal organs not covered by mesothelium

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6
Q

What layer of the GI tract differs considerably compared to the others. What is the function of the variability

A

Mucosa layer

Reflects functional activity & aids in ID of specific regions

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7
Q

What are the nerve plexuses of the GI system and where are they found

A
  1. Submucosal plexus of Meissner - Between submucosa & muscularis externa
  2. Myenteric plexus of Auerbach - Between inner circular and outer longitudinal layers of muscularis externa
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8
Q

What part of the parasympathetics increase motility

A

Preganglionic axons

Rest & digest

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9
Q

What part of the sympathetics decrease motility

A

Postganglionic axons

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10
Q

Esophagus:

What type of mucosa?

A

Nonkeratinized stratified squamous (protective)

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11
Q

What type of muscle is found in the muscularis layer of the esophagus

A

Upper third: skeletal (helps regulate voluntary demand of swallowing)

Middle third: skeletal and smooth

Lower third: smooth muscle

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12
Q

What causes Esophageal Varices

A

Inflammation of the submucosal venous plexuses leads to increase pressure of the portal venous system. This causes an increase in pressure of the veins in the esophagus causing the veins of the esophagus to become enlarged and dilated.

Lecture: Histology of the Esophagus & Stomach

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13
Q

Esophagus:

Is it serosa or adventitia?

A

Both!

Thoracic esophagus (above diaphragm): adventitia

Below diaphragm: serosa

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14
Q

Esophagus Glands

  1. What are they
  2. Where in the esophagus are they found
  3. What do they produce?
A
  • Cardiac esophageal glands
    • Lamina propria of terminal esophagus
    • produce mucus to protect esophagus from stomach contents
  • Submucosal glands
    • Throughout esophagus
    • Mucous and serous
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15
Q

What is the name of the functional sphincter that prevents reflux of gastric contents in the esophagus

A

Lower esophageal sphincter

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16
Q

What is Gastroesophageal reflux disease (GERD)/ Acid Reflux

A

Weaking of lower esophageal sphinceter resulting in backflow of gastric contents leading to chronic inflammation, ulceration & difficulty in swallowing (dysphagia).

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17
Q

What causes Barett’s esophagus

A

Chronic GERD causing nonkeratinized stratified squamous epithelium in transition zone to become columnar mucus-secreting/glandular epithelium in the esophagus.

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18
Q
  1. What is the change in epithelium that occurs when the GI tract transitions from the esophagus to stomach?
  2. What is this region called?
A
  1. Nonkeratinized stratified squamous epithelium –> simple columnar epithelium
  2. Gastroesophageal junction
19
Q

What are the four regions of the stomach?

A

Cardia, Fundus, Body & Pyloris

20
Q

What is the name of the longitudinal folds of the gastric mucosa that expand during filling of the stomach and what are they covered by?

A

Rugae

Gastric pits

21
Q

Stomach:

What kind of epithelium lines the mucosa?

A

Simple Columnar Epithelium

22
Q

What type of glands are found in the stomach and where are they found?

A

Cardiac, gastric & pyloric glands found in the lamina propria of the mucosa

23
Q

Stomach:

What kind of muscle is found in the muscularis externa layer?

A

1) Circular smooth muscle: forms pyloric sphincter
2) Longitudinal smooth muscle
3) Oblique smooth muscle: helps mix food

24
Q

Stomach:

Does it contain a serosa or adventitia layer?

A

Serosa

25
Q

What are the three parts of the fundic/gastric gland?

A

1) Gastric pit - invagination of the mucosal surface
2) Isthmus/neck - narrow region btw pit & gland
3) Gastric Gland - shorter & wider base

26
Q

What cells are found in Fundic (Gastric) Gland and which part of the fundus are they found?

A
  1. Surface mucous cells
  2. Mucous neck cells
  3. Pareital cells
  4. Chief cells
  5. G cells
27
Q

What mucous cell lines the lumen and gastric pit of the stomach?

A

Surface mucous cell

28
Q

What mucous cell is located in the neck, in singles and/or clusters in the stomach

A

Mucous neck cells

29
Q

What is the function of surface mucous & mucous neck cells?

A

They form an insoluble gel that attaches to the surface of gastric mucosa that neutralizes the microenvironment to an alkaline pH

30
Q

Where are Chief (Zymogenic) Cells found

A

Found in clusters in the inferior 1/3 of gastric gland

31
Q

What is the hallmark of Chief (Zymogenic) Cells

A
  • Abundant Rough endoplasmic reticulum and apical secretory (zymogen) granules
  • Basal nuclei with basophilic cytoplasm
32
Q

What do chief cells secrete and what is the function of the secretion?

A
  1. Pepsinogen –> Pepsin: Digest most proteins
  2. Gastric lipase: Digest lipids
33
Q

Where are parietal cells found in the stomach

A

Predominate near neck & upper segment of the gastric gland

34
Q

What are the hallmarks of Parietal Cells

A
  • Large cells, usually round or pyramidal-shaped
  • One (sometimes two) central round nucleus
  • Cytoplasm is esosinophilic due to increased mitochondria
35
Q

What do Parietal Cells secrete and what is the function of the secretion

A

Hydrochloric acid

Intrinsic factor - glycoprotein that binds to vitamnin B12

36
Q

What is the deep invagination at the apical plasma membrane of active parietal cells that increases the surface area for the production of gastric juice

A

Intracellular canaliculus

37
Q

What is a Gastric Ulcer and where does it occur

A

Painful erosive lesions of the mucosa that may extend to deeper layers. Can occur anywhere between the lower esophagus and portions of the small intestine

38
Q

What can cause a Gastric Ulcer

A
  • Bacterial infections with Helicobacter pylori
  • NSAIDS effects
  • Overproduction of HCl or pepsin
  • Lowered production or secretion of mucus or bicarbonate
39
Q

What is the name for the scattered epithelial cells in the gastric mucosa that play a major role in the digestive function

A

Enteroendocrine Cells

40
Q

What type of cells are Enteroendocrine Cells and what system are the considered a part of

A

Most are Amine precursor uptake & decarboxylation (APUD_ cells - process amines

Diffuse neuroendocrine system (DNES)

41
Q

What are the two kinds of Enteroendocrine Cells

A
  1. Closed type - cellular apex is covered by neighboring epithelial cells and is not exposed to GI lumen
  2. Open type - Apical end of the cell contacts the lumen and has chemoreceptors that sample limical contents
42
Q

What are Pyloric Glands

A

Branched, coiled, tubular glands of the pylorus

43
Q

What are tha hallmarks for pyloric glands

A
  • Lined by mucus-secreting cells with large and pale secretory mucus which neutralize acidity of from in stomach before going to a new segment of the GI tract
  • Glands empty into pits that occupy half of mucosa
  • Largely release gastrin from G cells
44
Q

What is the name of the lymphoid nodules in the pylorus that identify, recognize and respond to pathogens and antingens that may be ingested?

A

Gastric associates lymphatic tisse (GALT)

GIGU Exam 1 (25 decks)

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