Lecture 1 Flashcards

- Histology of the GIT

1
Q

What is the purpose of salivary glands?

A
  • produce saliva
  • secretes saliva into the oral cavity
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2
Q

What are salivary glands covered by and divided into? What is it made of?

A
  • capsule and lobules
  • connective tissue
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3
Q

How many salivary glands are there? What are they?

A
  • 3
  • Parotid, Sublingual, Submandibular
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4
Q

What type of cell lies deep to the basement membrane but superficial to the epithelium cells?

A

Myoepithelial cells

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5
Q

How many secreting units do acini have and what are they?

A
  • 3
  • Mucous, Serous, Mixed
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6
Q

What are the features of mucous acini cells?

A
  • Oval shaped, large lumen
  • Lined by columnar cells
  • Flattened nucleus at basement membrane
  • Contains large secretory granules of micinogen near the apex (in fresh condition- not present after staining)
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7
Q

What salivary gland contains majority of mucous acini?

A

Sublingual Gland

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8
Q

What are the features of serous acini cells?

A
  • Spherical, smaller than mucous acinus
  • Small lumen
  • Lined by columnar/pyramidal cells
  • Round nucleus at the basal part of the cell
  • Alpha-amylase (digestive enzyme) secreted by acinar cells
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9
Q

What salivary gland contains majority serous acini?

A

Parotid Gland

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10
Q

What are the features of mixed acini?

A
  • Spherical, smaller than mucous acinus
  • Small lumen
  • Lined by columnar/pyramidal cells
  • Round nucleus at the basal part of the cell
  • Alpha-amylase (digestive enzyme) secreted by acinar cells
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11
Q

What salivary gland contains mixed acini?

A

Submandibular Gland

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12
Q

How many surfaces does the tongue have and what are they?

A
  • 2
  • dorsal (top) and ventral (underside)
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13
Q

The tongue is covvered by a mucous membrane/ mucosa… how many layers does it have and what are they?

A
  • 2
  • Outer epithelium and inner lamina propria/corium
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14
Q

What type of epithelium is the tongue made up of?

A
  1. Stratified Squamous Non Keratinized epithelium
  2. Stratified Squamous Keratinized epithelium (over the papillae)
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15
Q

What is the lamina propria made of?

A
  • connective tissue
  • blood vessels
  • serous and mucous glands
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16
Q

How many lingual papillae are there and what are they?

A
  • 3
  • Filiform, Fungiform, Circumvallate
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17
Q

What are the features of filiform papillae?

A
  • ⅔ of the tongue
  • No taste buds
  • Small conical projections covered by horny keratinized cap
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18
Q

What are the features of fungiform papillae?

A
  • Rounded top; narrow base
  • Contains taste buds
  • Present at the apex and along the lateral margins of anterior
  • ⅔ of the dorsum of the tongue
19
Q

What are the features of circumvallate papillae?

A
  • 8 to 12 in number
  • Largest papilla, situated in a depression
  • Surrounded by the circular (vallate) sulcus
  • Have rounded top and narrow base
  • Contain taste buds on the their lateral wall
  • The sulcus receives the opening ducts of serous glands (Von Ebner’s gland)
  • Serous secretion of these glands distribute the substance to be tasted & wash out the debris in the sulcus
20
Q

What are the four layers of the alimentary canal?

A

Mucosa, Submucosa, Muscularis externa, Adventitia (esophagus & duodenum)/ Serosa (rest of GI tract)

21
Q

What are the features of the mucosa?

A

Consists of:
- epithelium: simple culomnar type
- lamina propria: loose areolar CT w/ glands, lymph vessels and lymph nodules
- muscularis mucosa: inner circular, outer longitudinal layers of smooth muscle

22
Q

What are the features of the submucosa layer?

A
  • irregular fibroelastic CT w/ elastic and collagen fibres
  • no glands (except in esophagus)
  • contains blood and lymph vessles and Meissner’s/ submucosal plexus of nerves
23
Q

What are the features of the muscularis externa layer?

A
  • inner circular, outer longitudinal layers of smooth muscle
  • Auerbach’s/ myenteric plexus of nerves situated between the two layers of smooth muscle
24
Q

What is the difference between the Serosa and Adventia layer?

A

Serosa: outermost layer formed by visceral peritoneum
Adventitia: outermost layer formed by CT coat (retroperitoneal)

25
Q

What type of epithelium does the esophagus contain?

A

Most of the esophagus: stratifies squamous non-keratinised epithelium
Lowest part of esophagus: simple columnar epithelium

26
Q

What type of glands does the esophagus contain?

A

Mucous glands lines by stratifies columnar cells
- secretes mucus which aids in the passage of food

27
Q

What type of muscle makes up different parts of the esophagus? (upper, middle, lower)

A

Upper: Skeletal
Middle: Both skeletal and smooth
Lower: Smooth

28
Q

How many parts of the stomach are there and what are they?

A
  • 4
  • Cardia, Fundus, Body, Pyloric part
29
Q

What are the longitudinal folds of mucosa on the interior of the stomach and what does it do?

A
  • gastric rugae
  • allows for distention of the stomach to allow more space when filled
30
Q

What do the gastric pits open into on the basal end of the epithelium?

A

Cardiac glands (2-3)

31
Q

What substances does the cardiac gland secrete?

A

mucous

32
Q

What is the importance of the cardiac glands?

A
  • Secretes mucous that lines the cardia which protects the esophagus from gastric reflux
  • part of the stomach’s gastric juice
33
Q

Why is the stomachs muscularis externa layer unique to the rest of the GIT?

A
  • 3 layers of smooth muscle as opposed to 2 layers
  • inner oblique (right side of muscularis propria), middle circular and outer longitudinal
34
Q

Gastric glands are lined by 3 types of cells. What are they?

A
  • Mucous Neck cells (mucous secretion)
  • Parietal cells (produce HCl)
  • Peptic/ Cheif cells (produce pepsin)
35
Q

Which parts of the GIT does adventitia replace serosa?

A

Esophagus and Duodenum

36
Q

Nueroendocrine/ G cells are found in lamina propria in the stomach wall. What hormone does it secrete?

A

Gastrin (primarily responsible for enhancing gastric mucosal growth, gastric motility, and secretion of hydrochloric acid (HCl) into the stomach)

37
Q

what are the 3 parts of the small intestine?

A

Duodenum, Jejunum, Ileum

38
Q

The mucosa of the small intestine forms tall projections. What are they called and what is its importance?

A
  • Villi
  • Increases surface area of the GIT wall for absorption of nutrients into the blood stream
39
Q

What are unique cells that are found in the epithelium of the small intestines and what is its function?

A
  • Goblet cells
  • secrete mucin and create a protective mucus layer
40
Q

What are the glands in the small intestine called?

A

Intestinal glands/ crypts of Lieberkhun

41
Q

Enterocytes (intestinal cells) are lined by 4 types of cells. What are they?

A
  • Goblet cells (mucin production)
  • Paneth cells (defensive in function)
  • Nueroendocrine cells (motility and secretion)
  • Stem cells
42
Q

How do you distinguish the duodenum from the jejunum using histology of the GIT?

A

The duodenum has brunners glands (mucous glands) located in the submucosa of the GIT wall

43
Q

How do you distinguish the jejunum from the ileum using histology of the GIT?

A

The ileum has Peyer’s patches (aggregated lymphoid follicles) located in the lamina propria; sometime break the muscularis mucosa layer and extend into the submucosa

44
Q

What is a unique feature of the appendix?

A

Contains agregated lymphoid follicles in the lamina propria layer of GIT wall; may extend through the muscularis mucosa into the submucosa layer