Digestive System III

Question 1

Glandular Stomach

Answer 1

• true stomach
• includes ruminant abomasum
• has 4 parts

Question 2

What are the 4 parts of the grandular stomach?

Answer 2

• cardia = transitional zone between esophagus and stomach
• fundus
• body
• pylorus = funnel shaped region opens into SI

Question 3

Where is gastric acid produced?

Answer 3

Fundus and Body of Stomach

Question 4

T/F: The glandular stomach shows all the layers of the GI tract.

Answer 4

True

Question 5

Rugae

Answer 5

• temporary folds in mucosa and submucosa of glandular stomach
• they flatten out when the stomach fills with food

Question 6

Mucosa of glandular stomach

Answer 6

• epithelium = simple columnar (mucus secreting)
• epithelium invaginates deeply into lamina propria = forms gastric pits
• invagination depths vary with different regions
• cells lining surface = surface mucous cells
• gastric glands open into gastric pits

Question 7

Cardiac Region of Glandular Stomach

Answer 7

• most extensive in pigs; minor in other species
• transition from stratified squamous to simple columnar epithelium
• gastric (cardiac) glands usually lined by mucus-secreting cells
• gastric pits are 1/3 of entire lamina propria (medium depth)

Question 8

Fundic Region of Glandular Stomach

Answer 8

-gastric pits are about 1/4 or less of lamina propria (relatively shallow)

Question 9

How many parts are in the gastric (fundic) gland?

What are they?

Answer 9

4

• Isthmus = opening of gland into pit above it
• Neck = constricted area near isthmus
• Body = main tube
• Base = dilated adenomere

Question 10

5 types of cells in fundic region

Answer 10

• chief (zymogen) cells
• parietal (oxyntic) cells
• mucus neck cells
• enteroendocrine cells
• germinal cells

Question 11

Chief Cells

Answer 11

• most numerous in lower region of gland
• foamy or lacy appearance
• stain light blue with H and E stain d/t RER
• pyramid-shaped with a basally positioned round nucleus
• apically positioned secretory granules (zymogen granules) present in fasted animals

Question 12

Secretions of Chief Cells

Answer 12

• pepsinogen = converted to pepsin, a proteolytic enzyme in acidic environment
• Rennin in young animals = curdles milk by coagulating casein
• gastric lipase

Question 13

Parietal Cells (Oxyntic Cells)

Answer 13

• bright-staining eosinophilic cytoplasm d/t mitochondria
• large cells scattered throughout gland from neck to base
• “wedged” between chief cells
• spheroidal shaped with round nucleus
• contain intracellular canaliculi that extend from apical plasma lemma into cytoplasm
• canaliculi are occluded by many microvilli

Question 14

What do parietal cells produce?

What stimulates the production of this product?

Answer 14

HCl

Stimulated by:

• cholinergic nerve endings
• gastrin
• histamine

Question 15

Mucus Neck Cells

Answer 15

• lines neck of gland
• interspersed among parietal cells
• Mucoid product is different than that of the surface mucus cells:
  
  • less viscous than surface lining mucus
  • contain acidic glycosaminoglycans

-protection from hydrolytic activity of HCl

Question 16

Enteroendocrine Cells

Answer 16

• endocrine/paracrine cells within enteric epithelium
• not limited to GI tract, but scattered all over body among epithelial cells
• stains with silver and chromium stains
• Examples in stomach
  
  • G cells secrete gastrin
  • D cells secrete somatostatin
  • EC cells secrete seratonin and substance P

Question 17

Germinal Cells

Answer 17

• stem cells

- found in gland neck and bottom of pits

Question 18

Pyloric Region

Answer 18

• gastric pits are 1/2 of lamina propria (deepest pits of all regions)
• histologically similar to cardiac gland
• contains muscular sphincter in most species at the gastroduodenal junction