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GI System > Histology > Flashcards

Histology Flashcards

1
Q

What are the three layers of the generalized gut mucosa?

A

1) Epithelium
2) Lamina Propria
3) Muscularis Mucosae

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2
Q

What types of epithelium exist in the generalized gut?

A

Either stratified squamous or simple columnar

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3
Q

Where is there no muscularis mucosa?

A

In the oral cavity, anal canal, or gall bladder

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4
Q

What is found in the submucosa of the generalized gut?

A

Dense irregular connective tissue and Meissner’s plexus of sympathetic and post-ganglionic parasympathetic fibers that innervate the muscularis mucosa

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5
Q

What are the two main layers of the Muscularis externa?

A

An inner circular layer (usually smooth, but skeletal in the mouth and esophagus)
Outer longitudinal layer (also smooth usually, but skeletal in mouth, esophagus and external anal sphincter)

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6
Q

What nerves supply the muscularis externa?

A

Auerbach’s plexus

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7
Q

What is the difference between a serosa and an adventitia?

A

If the organ has a mesothelium and is peritoneal, it has a serosa; if the organ is not peritoneal, the outer layer is an adventitia

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8
Q

What are the three types of oral mucosa, what features do they have, and where are they found?

A

1) Masticatory–has keratin, on gingiva and hard palate
2) Specialized–has keratin and papillae, on dorsal tongue
3) Lining–no keratin, robust and flexible; elsewhere in mouth

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9
Q

What are the four types of papillae found on the tongue? Which have taste buds and keratin?

A

1) Filiform–no taste buds, very keratinous
2) Fungiform–less numerous, has taste buds and some keratin
3) Circumvellate–papillae near terminal sulcus, has taste buds
4) Foliate–has taste buds, but poorly developed in humans

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10
Q

What structure cleanses taste buds?

A

The serous glands of von Ebner

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11
Q

What type of epithelium is found in the esophagus?

A

non-keratinized stratified squamous

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12
Q

What feature exists in the submucosa of the esophagus?

A

Esophageal glands that secrete mucus to lubricate esophagus

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13
Q

How does the muscularis externa appear histologically in the esophagus?

A

The proximal 1/3 is all skeletal muscle
The middle 1/3 is a transitional mix between skeletal and smooth muscle
The distal 1/3 is all smooth muscle

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14
Q

What are the four regions of the stomach?

A

The cardia, pylorus, fundus, and body

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15
Q

What type of epithelium exists in the stomach and what histological structure generates its acids and enzymes?

A

Simple columnar; gastric pits and glands

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16
Q

What is the purpose of rugae and where are they found histologically?

A

They are infoldings that allow the stomach to distend; found in the submucosa

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17
Q

What is unique about the stomach’s muscularis externa?

A

There is an additional layer of inner oblique muscles that promote additional churning

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18
Q

Which layer of the stomach’s muscularis externa forms the pyloric sphincter?

A

The middle circular

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19
Q

What types of cells are found in the pit region of the gastric pit? What do they make?

A

Surface mucus cells; secrete mucus

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20
Q

What types of cells are found in the neck region of the gastric gland? What do they make?

A

Mucus cells—mucus

Parietal cells–HCl and intrinsic factor (very eosinophilic)

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21
Q

What types of cells are found in the base region of the gastric gland? What do they make?

A

Predominantly chief cells–zymogens (very basophilic)

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22
Q

What are the main zymogens of the stomach and what are their roles?

A

Pepsinogen–protein digestion

Rennin/chymosin–curdle milk to slow digestion in infants

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23
Q

Where are G-cells found and what do they secrete?

A

In the body and pylorus of the stomach; gastrin

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24
Q

What are roles of gastrin?

A

Promotes parietal cell activity
Promotes chief cell activity
Promotes increased muscular contractions in the stomach

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25
Q

Where are D-cells found and what do they secrete? What prompts their secretions?

A

In the pylorus; somatostatin

Acids

26
Q

What is the main role of somatostatin?

A

Inhibition of G-cells and decrease of biliary and pancreatic secretions

27
Q

Where are ghrelin cells found and what is their role?

A

In the body; release ghrelin with low glucose to promote appetite

28
Q

How do gastric glands appear in the cardiac region of the stomach?

A
  • the pits are short
  • glands are long and coiled
  • secrete high levels of mucus
29
Q

How do gastric glands appear in the principal region of the stomach?

A
  • the pits are short
  • the glands are long and branched
  • have mucus, chief, and parietal cells
30
Q

How do gastric glands appear in the pyloric region of the stomach?

A
  • the pits are long
  • the glands are short and coiled
  • secrete high levels of mucus
31
Q

How does the small intestine increase its surface area?

A

1) pliae circulares–permanent folds of mucosa and submucosa (x3)
2) villi–finger projections of epithelium and lamina propria (x10)
3) microvilli–apical cellular projections (x20)

32
Q

What are the types of cells found in the crypts of Lieburkuhn?

A 
Enterocytes (absorption)
Goblet cells (mucus)
Stem cells
Paneth cells (anti-bacterial--small intestine only)
Enteroendocrine cells
33
Q

Where are goblet cells densest in the intestines?

A

Duodenum

34
Q

Where are S-cells found, what do they secrete, and what is that secretion’s function?

A

Duodenum; secretin; decrease acid in the stomach and promote bicarbonate secretions by the acinar pancreas

35
Q

Where are I-cells found, what do they secrete, and what is that secretion’s function?

A

Duodenum and jejunum; CCK; promote relaxation of the gallbladder to increase bile, increase trypsinogen release, decrease hunger

36
Q

What do E cells secrete and what is that secretion’s function?

A

Serotonin; promoted peristalsis

37
Q

How can the three segments of the small intestine be identified histologically?

A

The duodenum has Brunner’s glands—tubular mucus glands that secrete alkaline substances into the duodenum
Jejunum–lacks unique features
Ileum–has Peyer’s patches

38
Q

How can the appendix be identified histologically?

A

Looks much like the large intestines but lacks teniae coli and has many lymphoid nodules (NOT Peyer’s patches because they encircle entire organ)

39
Q

What are modifications of the large intestine’s epithelium compared to the small intestine?

A

deeper crypts of Lieberkuhn
higher mucus secretion
no villi nor microvilli

40
Q

What is the teniae coli?

A

Modulations of the outer longitudinal layer of the muscularis externa into three bands that permits independent contraction and compacts feces

41
Q

How much saliva do the main salivary glands produce daily?

A

Submandibular–600 mL
Parotid—300 mL
Sublingual 50 mL
Minro–50 mL

42
Q

What is the role of the stroma in the salivary gland?

A

Connective tissues that divide the gland into lobes and lobules

43
Q

What types of cells exist in the parenchyma of salivary glands and what are their roles?

A

1) Serous cells—pyramidal shaped, round nucleus, in acini, secrete enzymes
2) Mucus cells–columnar/pyramidal, flat nucleus, secrete mucin
3) Myoepithelial cells–contractile cells that surround secretory units

44
Q

What are the four stages of duct that saliva travels through?

A

1) Intercalcated ducts
2) Non-striated intralobar ducts OR striated intralobar ducts
3) Interlobular ducts
4) Main excretory duct

45
Q

What is the role of the intercalated duct? How does it appear histologically?

A

Made of simple cuboidal epithelium

Makes antibacterial lysozymes and lactoferrin

46
Q

What is the role of the non-striated interlobar duct? How does it appear histologically?

A

Made of simple columnar epithelium

Involved in mucus secreting glands

47
Q

What is the role of the striated interlobar duct? How does it appear histologically?

A

Made of simple columnar epithelium

Has a striated basal membrane with many mitochondria that change the tonicity of saliva by secreting K and HCO3

48
Q

Where are interlobular ducts found and how do they appear histologically?

A

They are in the septa; made of pseudostratified epithelia

49
Q

What is the predominant gland type found in the parotid gland? What is the excretory duct called? What does it make?

A
  • -serous acinar cells (have striated interlobar ducts)
  • -Stensen’s duct
  • -alpha-amylase and antimicrobial proteins
50
Q

What is the predominant gland type found in the submandibular gland? What is the excretory duct called? What does it make?

A
  • -tubuloacinar glands with serous demilunes
  • -mostly serous in nature, has striated interlobar ducts
  • -Wharton’s duct
  • -alpha-amylase, proline-rich proteins, lysozyme, mucus
51
Q

What is the predominant gland type found in the sublingual gland? What is the excretory duct called? What does it make?

A
  • -tubuloacinar gland; mostly mucosal
  • -non-striated interlobar ducts
  • -Bartholin’s duct
  • -mostly mucus production
52
Q

What are the two types of exocrine cells found in the pancreas and what do they produce?

A

Serous acini and ducts–most enzymes

Centro-acinar–HCO3-

53
Q

What are the components of the porta hepatis?

A

Hepatic portal vein
Hepatic artery
Lymphatic supply
Biliary duct (common hepatic)

54
Q

What is the name of the hepatic stroma and what type of connective tissue is present?

A

Glisson’s capsule

Type III collagen (reticular)

55
Q

What are distinguishing histological characteristics of hepatocytes?

A

–presence of glycogen granules and high levels of rough endoplasmic reticulum

56
Q

What are structural features of the sinusoids?

A
  • highly fenestrated cellularly and have fenestrated basement membrane
  • ferries both portal venous blood and arterial blood to central vein
57
Q

What do Kupffer cells do?

A

They are hepatic macrophages

58
Q

What is the space of Disse?

A

It is an actual space between sinusoids and hepatocytes where hepatic microvilli extend and extract nutrients and oxygen

59
Q

What are bile canaliculi?

A

small spaces surrounded by plasma membrane that receive bile from hepatocytes and ferries them to bile ducts

60
Q

How does the gallbladder appear histologically?

A

Simple columnar epithelium with microvilli; folded lamina propria, NO muscularis mucosa; very thick muscularis externa

GI System (6 decks)

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