Lecture #33: Upper GI Histology II Flashcards Preview

Histology -- Zach H. > Lecture #33: Upper GI Histology II > Flashcards

Flashcards in Lecture #33: Upper GI Histology II Deck (26):
1

What is the overall structure of gastric glands? 

  • simple branched tubular glands
  • narrow isthmus opens into bottom of a gastric pit
  • fundus (base) of the gland extends into the lamina propria
  • cell of the gastric glands: 
    • mucous neck cells 
    • stem cells in neck
    • chief cells (zymogenic cells)
    • parietal cells (oxyntic cells)
    • enteroendocrine cells (APUD cells)
      • amine precursor uptake and decarboxylation

2

What do mucous neck cells of gastric glands secrete? 

soluble mucous

3

Which cells, found in the neck of the gastric gland, replace other cells of the gastric pit? 

Stem Cells 

4

What do Chief cells (zymogenic cells) of gastric glands secrete? 

pepsinogen 

5

What do Parietal cells (oxyntic cells) of gastric glands manufacture and secrete? 

  • Manufacture -> HCl 
  • Secrete -> intrinsic factor 

6

What are enteroendocrine cells (APUD cells) of gastric glands and what do they secrete?

  • small cells with secretory vesicls polarized toward basal surface in proximity to blood vessels
  • produce:
    • peptide hormones 
    • serotonin 
  • diffuse neuroendocrine cells that secrete hormones

7

What are the characteristics of a parietal cell found in gastric glands? 

  • unique cell of the gastric glandj
  • large pyramidal shaped, eosinophilic cell
  • produces HCl and gastric intrinsic factor 
  • generates hydrogen ion from carbonic acid similar to osteoclast 
  • prominent intracellular canaliculi lined by microvilli 
  • tubulovesicle pools are part of exocytosis-endocytosis function

8

True or False: 

Parietal cells henerate hydrogen ions from carbonic acid similar to osteoclast. 

True 

9

Which ions are actively transported into the lumen of the canaliculus of parietal cells?

Cl-, H+, and K+

*the K+ ion is the recycled back into the cytoplasm*

10

When identifying between parietal and chief cells in a histomicrograph, which one appears eosinophilic?

parietal cell 

11

List the major structural featrues that increase surface area for absorption in the G.I. tract.

  • length of small and large intestine
  • Plicae circulares (valves of Kerckring)
  • Villi
  • Microvilli 

12

What are the 3 orders of folding that increase surface area in the small intestine? 

  1. Plicae 
  2. Crypt-villus System
  3. Microvilli 

13

What are plicae in the small intestine?

these are folds of the mucosa, each with a submucosal core

14

Describe the histology of the crypt-villus system.

  • each villus contains a core of lamina propria 
  • the crypts etend down between the villi below the bases of the villi 
  • crypts and villi constitute glands of the small intestine
  • the wall of villus is composed of a simple columnar epithelium with goblet cells 
  • each villus contains a capillary plexus 
  • each villus contains a blind-ending lymphatic referred to as a lacteal

15

What type of epithelium makes up the wall of the villus in the crypt-villus system of the small intestine? 

simple columnar epithelium with goblet cells 

16

Describe the fine structure of a microvillus. 

  • covered with glycoprotein and glycocalyx (glycolipid coat)
    • glycocalyx contains an array of brush-border enzymes:
      • maltase
      • sucrase
      • isomaltase
      • lactase
      • lipase
      • peptidases
      • produced by small intestinal epithelial cells 
    • bundles of actin filaments within microvillus is covered by a formin cap
  • supported by core of actin microfilaments 
    • actin filaments are tied to terminal web intermediate filaments (cytokeratins via spectrin fibrils 
    • actin filaments are bound to plasma membrane covering villus via membrane-linking proteins
      • myosin I and calmodulin 
    • actin filaments are bound to each other via actin corss-linking proteins
      • villin and fimbrin

17

Which 2 actin cross-linking proteins bind actin filaments to each other? 

  • villin 
  • fimbrin 

18

Which 2 membrane-linking proteins bind actin filaments to the plasma membrane covering the villus?  

  • myosin I 
  • calmodulin 

19

Which protein binds actin filaments to terminal web intermediate filaments (cytokeratins)? 

spectrin fibrils 

20

What kind of cap covers the bundles of actin filaments within the microvillus? 

formin cap

21

What glycolipid coat covers microvilli in the small intestine? 

Covered with glycoprotein and glycocalyx (glycolipid coat)

22

What brush-border enzymes are contained within the glycocalyx? 

  • maltase
  • sucrase
  • isomaltase
  • lactase
  • lipase
  • peptidases 

23

True or False: 

The crypts, of the crypt-villus system in the small intestine, extend down between the villi below the bases of the villi. 

True 

24

Do crypts and villi constitute glands of the small intestine? 

Yes 

25

Look at micrographs in lecture #33 and identify:

  • gastric pit
  • gastric gland
  • fundic portion of stomach
  • parietal cells 
  • chief cells 

26