Histology of the Esophagus & Stomach Flashcards

1
Q

4 Layers of GI Tract: Lumen –> Superficial

A

(1) Mucosa
(2) Submucosa
(3) Muscularis Externa
(4) Serosa/Adventitia

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2
Q

Serosa: Intraperitoneal or Retroperiotneal?

A

Intraperitoneal

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3
Q

Adventitia: Intraperitoneal or Retroperiotneal?

A

Retroperitoneal

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4
Q

3 Components of the Mucosal Layer:

A

(1) Lining Epithelium (varies segment to segment)
(2) Underlying Lamina Propria
(3) Muscularis Mucosae

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5
Q

Mucosal Layer: Lamina Propria

A
  • Vascularized, loose connective tissue
  • Contains lymphatic nodules and WBCs
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6
Q

Mucosal Layer: Muscularis Mucosae

A
  • Thin layer of smooth muscle that controls mobility and infoldings of mucosa
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7
Q

Submucosal Layer

A
  • Consists of a dense irregular connective tissue with neurovasculature and lymphatics
  • Nerve plexus associated with this layer
  • Glands may also be present (esophagus and duodenum)
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8
Q

Muscularis Externa

A
  • Two layers of smooth muscle
  • Neurovasculature plexuses located between layers
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9
Q

Muscularis Externa: Circular Layer

A
  • Inner layer
  • Function is to constrict the lumen
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10
Q

Muscularis Externa: Longitudinal Layer

A
  • Outer layer
  • Function is to shorten the tube
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11
Q

Serosa/Adventitia

A
  • GI tract is suspended by a mesentery/peritoneal fold
  • Organs may have adventitia and/or serosa
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12
Q

The Adventitial is covered by ___ and forms ____ layer

A
  • Mesothelium
  • Serosa
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13
Q

Areas without mesothelium covering have an:

A

Adventitia

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14
Q

What are the 4 Basic Mucosal Types?

A
  • Protective
  • Secretory
  • Absorptive
  • Absorptive + Protective
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15
Q

Mucosa Types: Protective

A
  • Nonkeratinized stratified squamous epithelium
  • Located in oral cavity, pharynx and anal canal
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16
Q

Mucosa Types: Absorptive

A
  • Simple columnar epithelium
  • Mucosa arranged as villi with crypts; glands may or may not be present
  • Located in SI
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17
Q

Mucosa Types: Secretory

A
  • Simple columnar epithelium
  • Mucosa is packed with glands
  • Located in Stomach
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18
Q

Mucosa Types: Absorptive + Protective

A
  • Simple columnar epithelium
  • Mucosa arranged into closely packed glands with extensive goblet cells
  • Located in LI
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19
Q

Two Plexuses of Sensory and Motor Neurons (Intrinsic/Enteric Innervation), linked by interneurons:

A

(1) Submucosal Plexus (of Meissner)
(2) Myenteric Plexus (of Auerbach)

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20
Q

Intrinsic/Enteric Innervation

A

Responsive to local stimuli and input from ANS

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21
Q

Intrinsic/Enteric Innervation Regulates and Controls:

A

(1) Peristaltic contractions of muscularis externa and movements of muscularis mucosae
(2) Secretory activities of mucosal and submucosal glands

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22
Q

Location of Myenteric Plexus:

A

Between the Circular Muscle and Longitudinal Muscle

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23
Q

Location of Submucosal Plexus:

A

Between the Submucosa and Circular Muscle

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24
Q

Preganglionic axons of the Parasympathetics ____ motility.

A

Increase

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25
Q

Postganglionic axons of the Sympathetics _____ motlity

A

Decrease

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26
Q

Esophagus

A
  • Fibromuscular tube that conveys food from oropharynx to stomach
  • Contains both Serosa and Adventitia
  • Contains both mucosal and submucosal glands that produce a thin layer of mucus to lubricate the epithelium
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27
Q

Part of Esophagus that has Adventitia:

A

Thoracic Esophagus

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28
Q

Part of Esophagus that has Serosa:

A

Inferior to Diaphragm

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29
Q

Glands of the Esophagus: Cardiac Esophageal Glands

A

Reside in the Lamina Propria of the terminal esophagus

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30
Q

Glands of the Esophagus: Submucosal Glands

A

Consist of small lobules with mucous and serous cell types

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31
Q

Esophagus: Mucosal Layer

A
  • Non-keratinized stratified squamous overlying a lamina propria
  • Numerous folds distend with food passage
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32
Q

Esophagus: Submucosal Layer

A
  • Network of collagen and elastic fibers
  • Contains many small blood vessels
  • Submucosal venous plexuses drain into both the systemic and portal venous system
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33
Q

Increased pressure in the Esophageal Submucosal Venous Plexuses can lead to:

A

Esophageal Varices (dilation of submucosal venous sinuses)

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34
Q

Esophagus: Muscularis Layer

A

Consists of inner circular layer and outer longitudinal layer; layers have segment-dependent variations

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35
Q

Muscularis Layer: Upper 1/3 Esophagus

A

Skeletal Muscle (Striated)

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36
Q

Muscularis Layer: Middle 2/3 Esophagus

A

Skeletal and Smooth Muscle

37
Q

Muscularis Layer: Lower 1/3 Esophagus

A

Smooth Muscle

38
Q

Lower Esophageal Spincter

A

Functional sphincter that prevents reflux of gastric contents

39
Q

Gastroesophageal Reflux Disease (GERD)

A

Causes chronic inflammation, ulceration, and difficulty in swallowing (dysphagia) due to reflux of gastric contents

40
Q

Barrett’s Esophagus

A
  • Result of chronic GERD
  • Nonkeratinized stratified squamous epithelium in the transition zone transform into columnar mucous secreting/glandular tissue
41
Q

Gastroesophageal Junction

A
  • Epithelial transition from esophagus to stomach
  • Nonkeratinized stratified squamous –> simple columnar
42
Q

Epithelium in the stomach is:

A

Glandular, with pits and glands

43
Q

4 Regions of the Stomach:

A

(1) Carida
(2) Fundus
(3) Body
(4) Pyloris

44
Q

Stomach: Cardia

A

2-3 cm near the esophageal opening

45
Q

Stomach: Fundus

A

Projects to the left of the cardia

46
Q

Stomach: Body

A

Extensive central region

47
Q

Stomach: Pyloris

A

Ends at gastroduodenal orifice

48
Q

Rugae

A
  • Longitudinal fold of the gastric mucosa and submucosa
  • Expand during filling of the stomach
  • Covered by gastric pits (contain gastric glands)
49
Q

Gastric Glands

A
  • Located in Gastric Pits
  • Produce a mucosal barrier to protect the mucosal surface
  • Shorter and wider base
50
Q

Stomach: Mucosa Layer

A
  • Simple columnar epithelium
  • Lamina propria contains cardiac, gastric, and pyloric glands
  • Reticular and collagen fibers predominate
  • Muscularis mucosae facilitates release of gastric gland secretions
51
Q

Stomach: Submucosal Layer

A
  • Dense irregular connective tissue with collagen and elastic fibers
  • Contains arterioles, venous plexuses and lymphatics
  • Meissner’s Plexus located here
52
Q

Stomach: Muscularis Externa

A
  • Consists of 3 layers of smooth muscle: oblique, circular and longitudinal
  • Circular muscle layer thickens in pyloric region
53
Q

Pyloric Sphincter

A

Thickening of circular muscle layer in the pyloris

54
Q

Stomach: Serosa

A

Loose connective tissue and blood vessels

55
Q

Fundic (Gastric) Glands

A
  • Simple (one opening), branched, tubular glands present throughout the gastric mucosa
  • Extend from bottom of gastric pits to muscularis mucosae (entire length of mucosa)
56
Q

Gastric Glands: Gastric Pit

A

Invaginations of the mucosal surface

57
Q

Gastric Glands: Isthmus/Neck

A

Narrow region between the gastric pit and gastric gland

58
Q

3 Regions of Fundic Glands:

A

(1) Gastric Pit
(2) Isthmus/Neck
(3) Gastric Gland

59
Q

2 Main Cell Types within the Gastric Pit of the Fundic Gland:

A

(1) Surface mucous cells
(2) Mucous neck cells

60
Q

2 Main Cell Types within the Isthmus/Neck of the Fundic Gland:

A

(1) Mucous neck cells
(2) Parietal cells

61
Q

2 Main Cell Types within the Gastric Gland of the Fundic Gland:

A

(1) Chief cells
(2) G cells

62
Q

2 Types of Mucous Cells:

A

(1) Surface Mucous Cells
(2) Mucous Neck Cells

63
Q

Surface Mucous Cells

A

Line the lumen of the stomach and gastric pits

64
Q

Mucous Neck Cells

A
  • Located in the neck, in singles and/or clusters
  • Round nuclei and apical secretory granules
65
Q

Function of Mucous Cells

A
  • Form an insoluble gel (mucins + water) that attaches to surface of gastric mucosa
  • Neutralizes the microenvironment to an alkaline pH (form bicarb ions)
66
Q

____ Nerve stimulation and ____ increase the secretion of soluble mucous by Mucous Neck Cells.

A
  • Vagal
  • ACh
67
Q

Chief (Zymogenic) Cells

A
  • Located in body of stomach; found in clusters in inferior 1/3 of gastric glands
  • Secrete Pepsinogen, but also produce Gastric Lipase (digests lipids)
68
Q

Hallmarks of Chief Cells

A
  • Abundant RER
  • Abundant apical secretory (zymogen) granules
  • Basal nuclei with basophilic cytoplasm
69
Q

Pepsinogen

A
  • Proenzyme stored in secretory granules in chief cells
  • Releases and converted to pepsin by acidic environment of stomach
  • Proteolytic enzyme that digests most proteins
  • Exocytosis of pepsinogen is rapid and stimulated by feeding
70
Q

Parietal Cells

A
  • Located in body of stomach; found near neck and upper segment of gastric gland
  • Produce HCl (gastric juice) and Intrinsic Factor (IF)
  • Active cells have deep invaginations of the apical plasma membrane
71
Q

Hallmarks of Parietal Cells

A
  • Large, typically round or pyramid-shaped
  • One (sometimes two) central round nuclei
  • Cytoplasm is eosinophilic due to large amount of mitochondria
72
Q

Intracellular Canaliculus

A
  • Found in active parietal cells
  • Deep invaginations of the apical plasma membrane – large SA produced by thousands of microvilli
73
Q

Intrinsic Factor

A
  • Secreted from Parietal Cells
  • Glycoprotein
  • Binds to Vitamin B12
74
Q

Gastric Ulcers

A
  • Painful erosive lesions of the mucosa that may extend to deeper layers
  • Occur between the lower esophagus and portions of the small intestine
  • Causes: bacterial infection with H. Pylori, NSAIDS, overproduction of HCl or Pepsin, lowered production or secretion of mucus or bicarb
75
Q

Enteroendocrine Cells

A
  • Scattered epithelial cells in the gastric mucosa
  • Produce hormones that are important in digestion
  • Release products that exert either paracrine or endocrine effects
76
Q

Most Enteroendocrine Cells are ____ cells that process ___

A
  • APUD (amine precursor uptake and decarboxylation)
  • Amines
77
Q

All Enteroendocrine Cells are considered part of the:

A

Diffuse Neuroendocrine System (DNES)

78
Q

Hormones Produced by Enteroendocrine Cells in the Fundus of the Stomach:

A
  • Ghrelin
  • Somatostatin
  • VIP
  • Gastrin (small amount)
79
Q

Hormones Produced by Enteroendocrine Cells in the Antrum of the Stomach:

A
  • Somatostatin
  • VIP
  • Gastrin
80
Q

Hormones Produced by Enteroendocrine Cells in the Duodenum:

A
  • Somatostatin
  • Motilin
  • GIP
  • VIP
  • Secretin
  • CCK
  • Gastrin
81
Q

Hormones Produced by Enteroendocrine Cells in the Jejunum:

A
  • Somatostatin
  • Motilin
  • GIP
  • VIP
  • Secretin
  • CCK
  • Gastrin (small amount)
82
Q

Hormones Produced by Enteroendocrine Cells in the Ileum:

A
  • Somatostatin
  • VIP
  • Secretin (small amount)
  • CCK (small amount)
83
Q

Hormones Produced by Enteroendocrine Cells in the Colon:

A
  • Somatostatin
  • VIP
84
Q

Enteroendocrine Cells: Closed Type

A
  • Cellular apex is covered by neighboring epithelial cells
  • Not exposed to GI lumen
85
Q

Enteroendocrine Cells: Open Type

A

Apical end of cell contacts the lumen and has chemoreceptors that sample luminal contents

86
Q

Effects of Hormones released from Enteroendocrine Cells:

A
  • Regulation of peristalsis and motility
  • Secretion of digestive enzymes, water and electrolytes
  • Sense of being satiated after eating
87
Q

Pyloric Glands

A
  • Branched, coiled, tubular glands of the pylorus
  • Largely release Gastrin from G Cells
  • Occasional Parietal Cells are present
  • Lymphoid nodules can be seen in the lamina propria (GALT)
88
Q

Pyloric Glands are lined by ___-___ cells with large and pale ___ mucus

A
  • Mucus-secreting
  • Secretory
89
Q

Pyloric Glands empty into ____ that occupy ___ of the mucosa

A
  • Pits
  • Half