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Gastroenterology > Histology of the Gastrointestinal System > Flashcards

Histology of the Gastrointestinal System Flashcards

1
Q

What are the four layers of the GI tract?

A

1) Mucosa
2) Submucosa
3) Muscularis externa
4) Serosa OR adventitia

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2
Q

What are the two layers of the muscularis externa?

A

Inner circular layer
Outer longitudinal layer

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3
Q

The mucosa of the esophagus is composed of…

A

Stratified squamous nonkeratinized epithelium

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4
Q

The mucus secreting glands of the esophagus are called the…

A

Esophageal cardiac glands (located at either end) and submucosal glands (located throughout)

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5
Q

What changes occur to the epithelium in Barrett’s esophagus?

A

The stratified squamous nonkeratinized epithelium is replaced by simple columnar epithelium typical of the stomach due to GERD

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6
Q

How do esophageal varices occur?

A
  • Hepatic portal hypertension leads to a back up of blood in the portal-systemic anastomisis between the stomach and distal esophagus
  • Venous blood is diverted from the stomach, which drains to the portal system, to the distal esophagus
  • This leads to esophageal vein dilation and varices
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7
Q

What two types of muscle does the muscularis externa of the esophagus have?

A

Striated muscle that transitions distally to smooth muscle

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8
Q

Is the esophagus surrounded by serosa or adventitia?

A
  • Serosa below the diaphragm, since it is intraperitoneal
  • Adventitia along the rest of its length
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9
Q

Why does esophageal cancer metastasize readily to other tissues?

A
  • Rich lympathic plexus
  • Not separated from other tissues by a serosa
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10
Q

Serosa vs adventitia

A

Digestive organs facing the peritoneal cavity have a serosa, and those that do not have an adventitia

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11
Q

How does the muscularis externa of the stomach differ?

A

It has a third innermost, oblique layer

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12
Q

Which layer forms the rugae of the stomach?

A

Submucosa

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13
Q

What change occurs at the esophagogastric junction?

A

The stratified squamous nonkeratinized epithelium is abruptly becomes simple columnar epithelium

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14
Q

What are gastric pits?

A

Invaginations of the epithelium in the stomach into the underlying LP
Opens at its neck into several gastric glands

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15
Q

What are the exocrine cells of the gastric mucosa and where do they secrete their products?

A
  • Surface mucous cells
  • Mucous neck cells
  • Parietal cells
  • Chief cells

Secrete into the lumen

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16
Q

What are the endocrine cells of the gastric mucosa and where do they secrete their products?

A
  • G-cells
  • D-cells

Secrete into their basal aspect into ISF of underlying lamina propria

17
Q

What is the clinical relevance of atrophic gastritis?

A

Autoimune destruction of parietal cells reduces intrinsic factor, impairing B12 absorption and leading to pernicous anemia

18
Q

What are the plicae circularis?

A

Transverse folds in the small intestine formed by the mucosa and submucosa in order to increase SA for nutrient absorption

19
Q

What are Brunner’s glands?

A

Mucous-secreting glands in the duodenum

20
Q

What are Peyer’s patches and where are they located?

A
  • MALT (mucosa-associate lymphoid tissues)
  • Located in the submucosa of the ileum
  • Protect against bacterial infection from the colon
21
Q

What are intestinal villi?

A
  • Formed by the mucosa in the SI
  • Consist of a core of LP covered by simple columnar epithelium
  • Form intestinal glands/crypts at the base
  • Increase SA
22
Q

What cells make up the microvilli or “brush border”?

A

The enterocytes

23
Q

What is the glycocalyx?

A

“Sugar coat” covering the microvilli containing enzymes that aid in digestion + absorption of carbs and proteins

24
Q

What is the function of goblet cells in the villi?

A

Produce mucins, which combine with water to form a protective mucous over the luminal surface of the SI

25
Q

What cells line the intestinal glands?

A

Paneth cells, enteroendocrine cells, M (microfold) cells, stem cells

26
Q

What are Paneth cells?

A
  • Secrete antimicrobial peptides as part of innate immunity
  • Stain reddish-pink
27
Q

What are M cells?

A
  • Present in the ileum and overly Peyer’s patches
  • Endocytose anitgens to intiate an immune response
28
Q

How does the mucosa of the colon differ from the SI?

A
  • Lacks villi
  • Forms deep tubular invaginations into the LP - intestinal glands
  • Epithelium is dominated by absorptive cells and goblet cells (++ goblet cells for lubricaton)
  • Epithelium still has simple columnar epithelium
  • Abrupt transition to stratified squamous epithelium at the rectoanal junction (pectineal line)

Gastroenterology (1 decks)

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