Lab9_GItract

Question 1

What are the layers of the stomach?

Answer 1

Mucosa:
- Pits and glands
1. Epithelium (simple columnar epithelium (with surface mucous cells → have mucigen droplets)
2. Lamina propria: loose CT
3. Muscularis mucosa: 2 layers of smooth muscles (inner circular/outer longitudinal)
- Occationaly 3 layers (outer circular)
- Smooth muscle projections in between glands in lamin propria

Subucosa:
- Dense irregular CT
- No glands, but rich in blood vessels, lymphatics & nerves

Tunica Muscular:
- 3 layers of smooth muscle (inner oblique/middle circular/outer longitudinale)

Serosa:
- Thin layer of loose CT covered by a mesothlium (simple squamous epithelium)

Question 2

WHat is the Pyloric ratio of pits : glands?

Answer 2

Pit has 2x length of glands (2:1)

Question 3

What is the Body ratio of pits : glands?

Answer 3

Gland is 4x the length of Pits (1:4)

Question 4

Which cells are seen in the body, but not in the pyloric region?

Answer 4

• Parietal cells
• Zymogenic cells

Question 5

What are the layers of the small intestine?

Answer 5

Mucosa:
- Crypt and villi
- Epithelium → Simple columnar epithelium with brush border
- Lamina Propria → loose CT
- Muscularis mucosa → 2 layers of smooth muscle (inner circular/outer longitudinal)

Submucosa:
- Dense irregular CT
- Brunner’s glands (mucous) in duodenum only
- Plicae circularis seen in jejunum

Tunica muscularis:
- 2 layers of smooth muscle (inner circular/outer longitudinal)

Adventitia or Serosa:
- Adventitia → dense irregular CT
- Serosa → thin layer of loose CT covered by mesothelium (simple squamous epithelium)

Question 6

What are all the different cells found in the brush border of the small intestine?

Answer 6

• Enterocytes
• Goblet cells
• Paneth cells
• Crypt base cells
• Enteroendocrine cells

Question 7

Which cells/glands are found in the submucosa of the small intestine?

Answer 7

Brunner’s glands (mucous) in duodenum only
Plicae circularis seen in jejunum

Question 8

What are the features of the Ileum?

Answer 8

• No Brunner’s gland
• No visible plicar circularis
• More Goblet cells
• Few Paneth cells
• Crypts and villi appear straight

Question 9

What are the layers of the large intestine?

Answer 9

Mucosa:
- No villi, only crypts (wich appear very straight in that region, and have no paneth cells, has goblet cells)
- Epithelium → simple columnar and contains mainly goblet cells
- Lamina Propria → Loose Irregular CT (like SI)
- Muscularis mucosa → 2 layers (inner circular/outer longitudinal like in SI)

Submucosa:
- Poorly preserved because very dense
- No place circularis

Tunica muscular:
- Inner circular
- Outer longitudinal (can be modified to form a 3rdlayer that runs the length of the colon) → called taenia coli and functions to strenghten longitudinal contractions

Serosa:
- Thins layer of loose CT covered by mesothelium (simple squamous epithelium)