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GIGU Midterm > Histology of the Esophagus and the Stomach > Flashcards

Histology of the Esophagus and the Stomach Flashcards

1
Q

What are the four different layers of the GI tract?

A

the mucosa, the submucosa, the muscularis externa, and the serosa/adventitia

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2
Q

which layer of the GI tract varies from region to region?

A

the mucosa

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3
Q

what are the three components of the mucosal layer of the GI tract?

A

the lining epithelium, the lamina propria, and the muscularis mucosae

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4
Q

what makes up the lamina propria?

A

vascularized loose connective tissue

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5
Q

what is found within the lamina propria?

A

lymphatic nodules and WBCs

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6
Q

what is the muscularis mucosae and what is its role?

A

it is a layer of smooth muscle that moves the mucosal layer that sits directly above it

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7
Q

what is the submucosal layer made up of?

A

dense irregular connective tissue with neurovasculature and lymphatics- glands can also be present in specific parts of the GI tract

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8
Q

what makes up the muscularis/ muscularis externa layer?

A

two layers of smooth muscle

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9
Q

what are the two layers of smooth muscle that make up the muscularis layer of the GI tract?

A

the inner circular layer and the outer longitudinal layer

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10
Q

contraction of the circular layer does what?

A

it constricts the lumen

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11
Q

contraction of the longitudinal layer does what?

A

it shortens the tube

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12
Q

how do you get a serosa layer?

A

when the GI tract is suspended by mesentery, the adventitia is covered by mesothelium and that forms the serosa

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13
Q

what are areas without a mesothelium covering called?

A

adventitia

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14
Q

What are the 4 main functions of the different mucosal types?

A

protective, secretory, absorptive, and absorptive/protective

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15
Q

what epithelium makes up the protective mucosa?

A

nonkeratinized stratified squamous epithelia

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16
Q

where is the protective mucosa found?

A

in the oral cavity, the pharynx, and the anal canal

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17
Q

what epithelium makes up the secretory mucosa?

A

simple columnar epithelium

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18
Q

where is the secretory mucosa found

A

in the stomach

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19
Q

what epithelium makes up the absorptive mucosa?

A

simple columnar epithelium

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20
Q

how is absorptive mucosa arranged?

A

as villi with crypts

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21
Q

where is absorptive mucosa found?

A

small intestine

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22
Q

what epithelium makes up the absorptive/protective mucosa?

A

simple columnar epithelium

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23
Q

how is the absorptive/protective mucosa arranged?

A

closely packed glands with goblet cells

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24
Q

where is the absorptive/protective mucosa found?

A

large intestine

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25
Q

we have two plexus that are responsible for regulating movements and secretions in the GI tract. What are they?

A

submucosal plexus of Meissner and myenteric plexus of Auerbach

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26
Q

where is the submucosal plexus of meissner positioned?

A

just deep to the submucosal layer of the GI tract- sits in between the submucosal layer and the muscularis layer

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27
Q

where is the myenteric plexus of Auerbach positioned?

A

it sits in between the inner and outer layers of the muscularis externa

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28
Q

what are the enteric plexuses responsible for?

A

they are responsive to local stimuli and input from the ANS; they regulate and control peristaltic contractions and secretory activities

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29
Q

does the esophagus have a serosa layer or an adventitia layer?

A

both; the thoracic esophagus has adventitia and inferior to the diaphragm the esophagus has a serosa layer

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30
Q

what glands are found in the esophagus?

A

mucosal and submucosal glands produce a thin layer of mucus to lubricate the epithelium

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31
Q

what gland is found in the lamina propria of the esophagus?

A

cardiac esophageal glands- in the terminal esophagus

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32
Q

what epithelium is found in the mucosal layer of the esophagus?

A

nonkeratinized stratified squamous epithelium

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33
Q

what is found within the submucosal layer of the esophagus?

A

the submucosal venous plexuses

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34
Q

what do the submucosal venous plexuses drain into?

A

the systemic and portal venous systems

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35
Q

the submucosal venous plexuses can become inflamed and increase pressure within the portal venous system which can cause what?

A

esophageal varices

36
Q

what muscle makes up the muscularis layer of the upper third esophagus?

A

skeletal muscle (striated)

37
Q

what muscle makes up the muscularis layer of the middle third esophagus?

A

skeletal and smooth muscle

38
Q

what muscle makes up the muscularis muscle of the lower third of the esophagus?

A

smooth muscle

39
Q

what is the role of the lower esophageal sphincter?

A

it prevents reflux of gastric contents

40
Q

what is caused by a weakening of the lower esophageal sphincter?

A

GERD

41
Q

what can GERD cause?

A

chronic inflammation, ulceration, and dysphagia due to reflux of gastric contents

42
Q

what happens when GERD becomes a chronic issue?

A

the non-keratinized stratified squamous epithelium of the esophagus is in a transition zone and it will become columnar mucus secreting/ glandular

43
Q

what is the chronic form of GERD known as?

A

Barrett’s esophagus

44
Q

what is the epithelial transition from the esophagus to the stomach known as?

A

the gastroesophageal junction

45
Q

what does the non-keratinized stratified squamous epithelium become when transitioning to the stomach?

A

simple columnar epithelium

46
Q

how is the epithelium in the stomach characterized?

A

glandular, with pits and glands

47
Q

what are the four regions of the stomach?

A

cardia, fundus, body, and pyloris

48
Q

what is rugae?

A

longitudinal folds of the gastric mucosa that expand during filling of the stomach

49
Q

what are rugae covered by?

A

gastric pits, which are openings into gastric glands

50
Q

what is found within the gastric glands?

A

the different cell types that we need in order to secrete the products necessary to produce our gastric contents

51
Q

where are the cardiac, gastric, and pyloric glands found in the stomach?

A

in the lamina propria of the mucosal layer

52
Q

what facilitates the release of the gastric gland secretions?

A

the muscularis mucosae in the mucosal layer

53
Q

what makes up the muscularis layer of the stomach?

A

3 layers of smooth muscle: oblique, circular, and longitudinal

54
Q

what forms the pyloric sphincter?

A

the circular muscle layer thickening in the pyloric region

55
Q

what are the characteristics of the gastric glands?

A

simple, branched, tubular glands

56
Q

what are the three parts of the gastric glands?

A

the gastric pit, the isthmus/neck, and the gastric gland (the base)

57
Q

what are the cells that line the gastric glands?

A

mucosal cells, chief cells, parietal cells, enteroendocrine cells

58
Q

there are two different types of mucous cells. What are they?

A

surface mucous cells and mucous neck cells

59
Q

where are surface mucous cells located?

A

they line the lumen and gastric pits

60
Q

where are the mucous neck cells located?

A

they are located in the neck of the gastric gland in singles or clusters

61
Q

what do mucous cells secrete?

A

a mucous layer containing 95% water and 5% mucin

62
Q

what is the purpose of mucous?

A

it serves as a thick coating that neutralizes the microenvironment to an alkaline pH

63
Q

where are chief (zymogenic) cells located?

A

they are found in clusters in the inferior 1/3 of gastric glands

64
Q

how can you identify chief cells on a histologic stain?

A

they have an abundant RER and apical secretory (zymogen) granules; dark staining cytoplasm

65
Q

what do chief cells secrete?

A

pepsinogen

66
Q

what is pepsinogen?

A

the proenzyme that is stored in secretory granules; when it is released it is converted to pepsin by the acidic environment

67
Q

what is the role of pepsinogen/pepsin?

A

it is a proteolytic enzyme that digests most proteins

68
Q

what is exocytosis of pepsinogen stimulated by?

A

feeding

69
Q

what else can chief cells produce and what is the role?

A

gastric lipase, which digests many lipids

70
Q

where are parietal cells found?

A

they are predominately found near the neck and upper segment of the gastric gland

71
Q

what do parietal cells produce?

A

hydrochloric acid and intrinsic factor

72
Q

what is intrinsic factor?

A

a glycoprotein that binds to vitamin B12

73
Q

what are the hallmarks of parietal cells?

A

large cells, usually round or pyramidal-shaped, one (sometimes two) central round nucleus, cytoplasm is eosinophilic due to increased mitochondria

74
Q

what is the deep invagination of the apical plasma membrane that is found within active parietal cells?

A

intracellular canaliculus- increases the surface area

75
Q

what are gastric ulcers?

A

painful erosive lesions of the mucosa that may extend to deeper layers

76
Q

what can cause gastric ulcers?

A

bacterial infections with H. pylori, effects of NSAIDS, overproduction of HCl or pepsin, and lowered production or secretion of mucus or bicarbonate

77
Q

what are enteroendocrine cells?

A

scattered epithelial cells in the gastric mucosa with very distinct functions because they produce hormone products

78
Q

what are most enteroendocrine cells?

A

APUD cells: they process amines

79
Q

what are all of the enteroendocrine cells considered to be a part of?

A

the diffuse neuroendocrine system (DNES)

80
Q

what are the two types of enteroendocrine cells?

A

closed type or open type

81
Q

what are the closed type of enteroendocrine cells?

A

the cellular apex is covered by neighboring epithelial cells and they are not exposed to the GI lumen

82
Q

what are the open type of enteroendocrine cells?

A

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

83
Q

what are the general characteristics of pyloric glands?

A

branched, coiled, tubular glands of the pylorus

84
Q

what are pyloric glands lined by?

A

mucus-secreting cells with large and pale secretory mucus

85
Q

what do the pyloric glands empty into?

A

into pits that occupy half of mucosa

86
Q

what do the pyloric glands release?

A

gastrin from G cells

87
Q

what can be seen in the lamina propria of the pylorus?

A

lymphoid nodules- GALT

GIGU Midterm (19 decks)

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