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Histology Exam III Material > Lower GI I > Flashcards

Lower GI I Flashcards

1
Q

Layers of the intestinal wall (from inside to outside)

A
  • Mucosa with lamina propria and muscularis mucosa
  • Submucosa
  • Muscularis layers
  • Serosa
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2
Q

Histologic Characteristics of Duodenum

A
  • Villi with wide spatulate or “leaflike” distal shape
  • Deep crypts of Lieberkuhn
  • Brunner’s glands with excretory ducts in submucosa
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3
Q

Crypts of Lieberkuhn are _______ ______ glands within the _________

A

simple tubular glands, intestinal mucosa

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4
Q

Crypts of lieberkuhn open between adjacent ______ and extend to ________ _______

A

villi, muscularis mucosa

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5
Q

Cell of the crypts of Lieberkuhn

A

Goblet cells
Enterocytes
Paneth cells
Enteroendocrine cells

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6
Q

Enterocytes are _______ epithelial cells

A

columnar

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7
Q

Characteristics of Enterocytes

A
  • Basal nucleus, perinuclear Golgi, apical brush border
  • Produce disaccharidases
  • Involved in absorption of proteins, carbohydrates, and lipids
  • Enzymes present on apical brush border are important in carbohydrate digestion
  • Produce enteropeptidase (enterokinase) which is necessary for the activation of pancreatic zymogens and proenzymes
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8
Q

Enterocytes produce

A

Disaccharidases and enteropeptidase (enterokinase)

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9
Q

______ is produced by enterocytes and necessary for the activation of pancreatic zymogens and proenzymes

A

Enteropeptidase (enterokinase)

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10
Q

Characteristics of Paneth cells

A
  • Basal crypt cells
  • Prominent eosinophilic granules
  • Produce lysozyme to control intestinal flora
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11
Q

basal crypt cells with prominent eosinophilic granules

A

Paneth cells

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12
Q

Characteristics of Enteroendocrine cells

A
  • Stain with chromium (chromaffin)
  • Agyrophilic (respond to silver stains)
  • Produce peptide hormones and serotonin
  • May produce pancrine or autocrine secretions
  • Analogous to unicellular goblet cells
  • formed from endodermal stem cells in all regions of the GI tract
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13
Q

Enteroendocrin cells of the crypts of Lieberkuhn produce

A

peptide hormones and serotonin

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14
Q

What are enteroendocrine cells mode of secretion

A

paracrine or autocrine secretions

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15
Q

Brunner glands are found in

A

submucosa of duodenum

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16
Q

Brunner’s glands are responsible for

A
  • Formation of bicarbonate and mucus
    • Supplements bicarbonate from the pancreas
      - Necessary to neutralize gastric acid
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17
Q

Histological Characteristics of Jejunum

A
  • Villi longer and more narrow than in Duodenum
  • Crypts of Lieberkuhn present
  • No glands in submucosa
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18
Q

Histologic characteristics of Ileum

A
  • Villi are longer and narrower than in jejunum
  • Crypts of Lieberkuhn present
  • No glands in submucosa
  • Peyer’s patches
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19
Q

Epithelium of large intestine

A
  • Simple columnar epithelium

- Crypts but no villi

20
Q

Functions of large intestine

A
  • Secretion of mucus for lubrication
  • Goblet cell is the prominent cell of the large intestine
  • Absorption of fluid
  • Formation of fecal mass
  • Continuation of digestion initiated in small intestine
21
Q

Location of M cells (antigen-presenting cells)

A

Ileum

22
Q

The epithelial cells of the GI tract are held together by _______ containing the transmembrane proteins ____ and _____, which function to prevent paracellular transport

A

occluding junctions, claudins and occludins

23
Q

Characteristics of Paneth Cells

A
  • Basophilic basal cytoplasm
  • Supranuclear Golgi complex
  • Large, intensely acidophilic apical secretory granules
24
Q

Paneth cells secrete (what are the functions of each secretion)

A

Lysozyme- increase permeability of bacteria by degrading peptidoglycan goat

  • Defensins to increase membrane permeability of target organism
  • Tumor necrosis factor- alpha (proinflammatory cytokine)
    • may phagocytize some microorganims and help regulate intestinal flora
25
Q

What are the three regions of the small intestine

A

Duodenum
Jejunum
Ileum

26
Q

______ layer coats intestinal epithelial luminal surface

A

mucosal

27
Q

The mucosal layer of intestines is secreted by

A

goblet cells

28
Q

The mucosal layer of intestines is made up of how many layer and what are they

A

It is made up of 2 layers

  • Outer layer contains microorganisms
  • Inner layer contains:
    • Antimicrobial proteins (from Paneth Cells, Enterocytes, and Goblet cells ) that resist microbial penetration
29
Q

Toll-like receptors are found on the surface of

A

enterocytes

30
Q

What are toll-like receptors

A

They are found on the surface of enterocytes
fxn:
- Type of pattern recognition receptor
- Recognize structurally conserved molecules broadly shared by pathogens but distinguish from host molecules (pathogen associated molecular patterns (PAMPs))

31
Q

Explain the immune surveillance system with toll-like receptors

A
  • Antigen binds to toll-like receptor on enterocyte surface
  • —> B cell-activating factor is produced
  • ——> B cells in lamina propria mature into plasma cells (antibodies)
32
Q

Explain the immune surveillance system with M cells

A
  • Antigen is taken up by M (microfold) cells associated with Peyer patch in the intestinal mucosa
  • —–> Antigens are transported to lymphocytes located in pockets in folds of M cells
  • ———-> Antigens are bound to Ig receptors on surface of lymphocytes
  • —————> Lymphocytes transfer Ig-bound antigen to dendritic cells in lamina propria
  • ——————> Dendritic cells interact with T cells in lamina propria to activate immune response
33
Q

The bulk of the body’s immune defenses is centered in the

A

GALT (gut associated lymphatic tissue)

34
Q

Components of GALT

A
  • Transitory aggregations of lymphocytes, neutrophils, eosinophils
  • Permanent structures:
    • Appendix
    • Peyer’s patches
    • Mesenteric lymph nodes
35
Q

The antigen-presenting cells (APCs) and macrophages of Peyer’s patches phagocytize the antigen and present it to ____ and ______ cells as well as _______

A

helper and cytoxic T cells as well as B lymphocytes

36
Q

what is the function of M cells

A

Associated with Peyer’s patches

- sample particular antigen and present it to antigen-presenting cells in the underlying lamina propria

37
Q

What are Peyer’s Patches

A
  • A permanent GALT found in the ileum
  • Dome-shaped lymphoid structures
  • Contain B- and T-cell dependent area
  • Possess high endothelial venules (HEVs), which facilitate entrance of lymphocytes into lymphoid organs form the bloodstream
38
Q

The primary immunoglobulin produced by GALT is ____

A

IgA (secretory IgA, slgA)

39
Q

IgA is synthesized and secreted by _____ cells in the lamina proper of the gut and picked up at the ____ surface of enterocytes and transported across the cell

A

plasma, Basal

40
Q

while in the enterocyte, slgA is linked to a protein called ______ that inhibits degradation of the saga by proteolytic enzymes in the GI lumen

A

Secretory component

41
Q

Secretory IgA, unlike IgG, does not stimulate the _______ but function by

A

complement system, but functions by coating microorganisms, thus inhibiting microorganisms binding to the epithelium

42
Q

Rapid cell turnover is a ______ mechanism used by the GI epithelium

A

Protective (particularly true of stomach and small intestine)

43
Q

Lining of most GI tract is replaced every ____ days

A

5

44
Q

New cells of the small intestine are formed in

A

the crypts from undifferentiated cells

45
Q

new cells in the esophagus and anus

A

are formed in the basal layer of stratified epithelium and migrate through sub-basal levels to be sloughed off into the lumen

46
Q

Proliferative compartment of large intestine is found in the

A

base of the crypts

47
Q

Stem cells are found in what part of the stomach and differentiate into

A
  • stem cells are found in the neck of the gastric glands
  • differentiate into
    • surface and neck mucus cells (turn over most rapidy)
    • Enteroendocrine cells
    • Parietal cells
    • Chief cells

Histology Exam III Material (15 decks)

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