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A. White- Histology > Lower GI Histology > Flashcards

Lower GI Histology Flashcards

1
Q

What are the layers of the intestinal wall?

A

From inside to outside:

mucosa with lamina propria and muscularis mucosa

submucosa

muscularis layers

serosa

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2
Q

In what layer of the intestine are the villi and crypts found?

A

mucosa

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3
Q

What lymphatic plexus is found in the villi?

A

lacteal.

They have branches that surround a lymphoid nodule in the submucosa.

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4
Q

What are characteristics of the duodenum?

A

It has villi with a wide, leaflike shape

Deep crypths of lieberkuhn

Brunner’s glands with excretory ducts in submucosa

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5
Q

What gland is found only in the muscularis mucosae of the duodenum?

A

Brunner’s gland

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6
Q

What patch is found only in the submucosa of the ileum?

A

Peyer’s patches. They are lymphoid aggregates.

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7
Q

What are the crypts of liberkuhn?

A

Simple tubular glands within the intestinal mucosa.

They open between adjacent villi and extend to muscularis mucosa.

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8
Q

What cells are found in the crypts of lieberkuhn?

A

Goblet cells

Enterocytes

Paneth cells

Enteroendocrine cells

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9
Q

What are physical characteristics of the crypts of lieberkuhn?

A

Basal nucleus

Perinuclear Golgi

Apical brush border

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10
Q

What is the function of enterocytes?

A

production of disaccharidases

Absorption of proteins, carbohydrates and lipids.

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11
Q

Enzymes present on the apical border of the enterocytes are important in what?

A

carbohydrate digestion

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12
Q

What enzyme produced by enterocytes is necessary for the activation of pancreatic zymogens and proenzymes?

A

enteropeptidase

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13
Q

What enzyme do paneth cells produce?

A

lysozyme; it controls the intestinal flora.

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14
Q

Where are paneth cells found?

A

in the crypt (basal area)

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15
Q

What type of blood component is found in the paneth cells?

A

eosinophilic granules

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16
Q

What do enteroendrocrine cells produce?

A

peptide hormones and serotonin.

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17
Q

You are studying the GI tract and obtain a sample of endodermal stem cells. What will these stem cells differentiate into?

A

enteroendocrine cells.

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18
Q

Where are the glands of Brunner found?

A

submucosa of duodenum

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19
Q

What are the glands of brunner responsible for?

A

Formation of bicarbonate and mucus.

They are also necessary to neutralize gastric acid.

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20
Q

What are the histologic characteristics of the jejunum?

A

Long and narrow villi

Crypts of Lieberkuhn present

No glands in submucosa

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21
Q

What are the histologic characteristics of the ileum?

A

Long and narrow villi

Crypts of Lieberkuhn Present

No glands in submucosa

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22
Q

The large intestine is comprised of what type of epithelium?

A

simple columnar

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23
Q

The large intestine contains ____, but no ____

A

crypts, villi

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24
Q

Why does the large intestine secrete mucus?

A

for lubrication.

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25
Q

What is the prominent cell of the large intestine?

A

goblet cells

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26
Q

What are three functions of the large intestine?

A

Absorption of fluid

Formation of fecal mass

Continuation of digestion initiated in small intestine.

27
Q

What type of junctions are found between intestinal cells?

A

Tight junctions.

THey are occluding junctions that contain claudins and occludins.

28
Q

What do the occluding junctions between the intestinal junctions prevent?

A

paracellular transport.

29
Q

If there is a defect in the tight junctions, what is able to pass inbetween the junctions?

A

lamina propria.

30
Q

Paneth cells contain what blood componentn?

A

basophils

31
Q

Paneth cells contain what type of secretory granules at the apical surface?

A

acidophilic secretory granules

32
Q

What do patheth cells secrete

A

Lysozyme

Defensins

Tumor necrosis factor alpha

33
Q

You are studying the GI tract and introduce foreign bacteria to it. What enzyme is secreted to attack the bacteria, and what type of cell secretes it?

A

Lysozyme is secreted by the paneth cells in order to degrade bacteria.

34
Q

What is the purpose of the secretion of defensins by paneth ells?

A

It increases membrane permeability of target organisms.

35
Q

Paneth cells secrete various enzymes and proteins. What is another function of paneth cells?

A

To phagocytize some microorganisms and help regulate intestinal flora.

36
Q

What does the mucosal layer coat?

A

Intestinal epithelial luminal surface.

37
Q

What are the two layers of the mucosal layer?

A

outer layer (microorganisms)

Inner layer: antimicrobial proteins that resist microbial penetration.

38
Q

Where are toll-like receptors found?

A

on the surface of enterocytes.

39
Q

What do toll-like receptors recognize?

A

structurally conserved molecules broadly shared by pathogens but distinguishable from host molecules.

40
Q

What is the pattern of the immune surveillance syste?

A
  1. Antigen binds to toll-like receptor on enterocyte surface.
  2. B-cell activating factor is produced
  3. B cells in lamina propria mature into plasma cells -> antibodies.
41
Q

Once B cells mature into plamsa cells (antibodies), what happens to the antigen?

A

It is taken up by M cells associated with Peyer patch in the intestinal mucosa.

42
Q

Once antigens are taken up by M cells, where are the antigens transported?

A

to lymphocytes located in pockets in folds of M cells.

43
Q

Once antigens are transported to lymphocytes, what do the antigens bind to on the surface of lymphocytes?

A

Ig receptors.

44
Q

Once antigens are bound to Ig receptors on lymphocytes, where is the Ig bound antigen transferred?

A

to dendritic cells in lamina propria.

45
Q

When lymphocytes are transferred to dendritic cells in the lamina propria, what do the dendritic cells then do?

A

interact with T cells in lamina propria to activate an immune response.

46
Q

Where is the bulk of the body’s immune defenses centered?

A

GALT

47
Q

What are the permenant structures in the GALT?

A

appendix

Peyer’s patches

Mesenteric lymph nodes

48
Q

What does GALT contain?

A

lymphocytes

neutrophils

eosinophils

49
Q

In what region of the villi are peyer’s patches found?

A

submucosa (under mucosal surface)

50
Q

What type of cells are found in peyer’s patches?

A

B and T cells

51
Q

Peyer’s patches contain high endothelial venules. What do HEVs do?

A

allow the entrace of lymphocytes into lymphoid organs from the bloodstream.

52
Q

What is found on the mucosal covering of Peyer’s patches?

A

M (microfold cells).

They take particulate of an antigen and present it to antigen-presenting cells in the underlying lamina propria.

53
Q

What do antigen presenting cells do?

A

phagocytize an antigen and present it to helper and cytotoxic T cells, as well as B lymphocytes.

54
Q

What is the primary immunoglobulin produced by GALT?

A

IgA

55
Q

Where are IgA immunoglobulins synthesized and secreted?

A

They are secreted by plama cells in the lamina propria of the gut.

They are picked up at the basal surface of enterocytes and transported across the cell.

56
Q

When in the cell, what is sIgA bound to in order to prevent degradation by proteolytic enzymes?

A

secretory component protein

57
Q

What is the function of secretory IgA?

A

It coats microorganisms, which inhibits microorganisms from binding to the epithelium.

58
Q

What is a protective mechanism used by the GI epithelium?

A

rapid cell turnover.

59
Q

How often is the lining of the stomach and small intestine replaced?

A

Every five days

60
Q

In the esophagus, where are new cells formed?

A

in the basal layer of stratified epithelium.

61
Q

Where are new cells formed in the small intestine?

A

in the crypts

62
Q

Where is the proliferative compartment found in the large intestine?

A

At the base of the crypt.

63
Q

What cells in the stomach are responsible for cell turnover?

A

surface and neck mucus cells

Enteroendocrine cells

Parietal cells

Chief cells.

64
Q

What does the small intestine consist of?

A

Duodenum

Jejunum

Ileum

A. White- Histology (25 decks)

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