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
What type of epithelium does the esophagus contain?
Most of the esophagus: stratifies squamous non-keratinised epithelium Lowest part of esophagus: simple columnar epithelium
26
What type of glands does the esophagus contain?
Mucous glands lines by stratifies columnar cells - secretes mucus which aids in the passage of food
27
What type of muscle makes up different parts of the esophagus? (upper, middle, lower)
Upper: Skeletal Middle: Both skeletal and smooth Lower: Smooth
28
How many parts of the stomach are there and what are they?
- 4 - Cardia, Fundus, Body, Pyloric part
29
What are the longitudinal folds of mucosa on the interior of the stomach and what does it do?
- gastric rugae - allows for distention of the stomach to allow more space when filled
30
What do the gastric pits open into on the basal end of the epithelium?
Cardiac glands (2-3)
31
What substances does the cardiac gland secrete?
mucous
32
What is the importance of the cardiac glands?
- Secretes mucous that lines the cardia which protects the esophagus from gastric reflux - part of the stomach's gastric juice
33
Why is the stomachs muscularis externa layer unique to the rest of the GIT?
- 3 layers of smooth muscle as opposed to 2 layers - inner oblique (right side of muscularis propria), middle circular and outer longitudinal
34
Gastric glands are lined by 3 types of cells. What are they?
- Mucous Neck cells (mucous secretion) - Parietal cells (produce HCl) - Peptic/ Cheif cells (produce pepsin)
35
Which parts of the GIT does adventitia replace serosa?
Esophagus and Duodenum
36
Nueroendocrine/ G cells are found in lamina propria in the stomach wall. What hormone does it secrete?
Gastrin (primarily responsible for enhancing gastric mucosal growth, gastric motility, and secretion of hydrochloric acid (HCl) into the stomach)
37
what are the 3 parts of the small intestine?
Duodenum, Jejunum, Ileum
38
The mucosa of the small intestine forms tall projections. What are they called and what is its importance?
- Villi - Increases surface area of the GIT wall for absorption of nutrients into the blood stream
39
What are unique cells that are found in the epithelium of the small intestines and what is its function?
- Goblet cells - secrete mucin and create a protective mucus layer
40
What are the glands in the small intestine called?
Intestinal glands/ crypts of Lieberkhun
41
Enterocytes (intestinal cells) are lined by 4 types of cells. What are they?
- Goblet cells (mucin production) - Paneth cells (defensive in function) - Nueroendocrine cells (motility and secretion) - Stem cells
42
How do you distinguish the duodenum from the jejunum using histology of the GIT?
The duodenum has brunners glands (mucous glands) located in the submucosa of the GIT wall
43
How do you distinguish the jejunum from the ileum using histology of the GIT?
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
What is a unique feature of the appendix?
Contains agregated lymphoid follicles in the lamina propria layer of GIT wall; may extend through the muscularis mucosa into the submucosa layer