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)
Loading flashcards...
1
Q

What is the overall structure of gastric glands?

A
  • 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
Q

What do mucous neck cells of gastric glands secrete?

A

soluble mucous

3
Q

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

A

Stem Cells

4
Q

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

A

pepsinogen

5
Q

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

A
  • Manufacture -> HCl
  • Secrete -> intrinsic factor
6
Q

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

A
  • 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
Q

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

A
  • 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
Q

True or False:

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

A

True

9
Q

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

A

Cl-, H+, and K+

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

10
Q

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

A

parietal cell

11
Q

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

A
  • length of small and large intestine
  • Plicae circulares (valves of Kerckring)
  • Villi
  • Microvilli
12
Q

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

A
  1. Plicae
  2. Crypt-villus System
  3. Microvilli
13
Q

What are plicae in the small intestine?

A

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

14
Q

Describe the histology of the crypt-villus system.

A
  • 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
Q

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

A

simple columnar epithelium with goblet cells

16
Q

Describe the fine structure of a microvillus.

A
  • 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
Q

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

A
  • villin
  • fimbrin
18
Q

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

A
  • myosin I
  • calmodulin
19
Q

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

A

spectrin fibrils

20
Q

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

A

formin cap

21
Q

What glycolipid coat covers microvilli in the small intestine?

A

Covered with glycoprotein and glycocalyx (glycolipid coat)

22
Q

What brush-border enzymes are contained within the glycocalyx?

A
  • maltase
  • sucrase
  • isomaltase
  • lactase
  • lipase
  • peptidases
23
Q

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.

A

True

24
Q

Do crypts and villi constitute glands of the small intestine?

A

Yes

25
Q

Look at micrographs in lecture #33 and identify:

  • gastric pit
  • gastric gland
  • fundic portion of stomach
  • parietal cells
  • chief cells
A
26
Q
A