Lecture 19: GI Anatomy + Organization

Question 1

Enteric NS

Answer 1

Neural crest derived subdivision of ANS. Innervates gut brain axis

Question 2

Embryonic divisions of the gut

Answer 2

1. Foregut
2. Midgut
3. Hindgut

Question 3

Gut innervation

Answer 3

1. Myenteric (Auerbach’s) plexus between ICL, OLL
2. Submucosal (Meissner’s) plexus in submucosa

Question 4

Neural crest cell migration to gut tube

Answer 4

2 pathways:
1. Vagal
2. Lumbosacral (rectum)
Migrate along gut tube, meet and overlap in distal colon

Question 5

Congenital megacolon

Answer 5

Large distension and immobile feces due to gut paralysis from incomplete neural crest migration -> lack of innervation

Question 6

Esophagus features

Answer 6

• SSNK
• Esophageal cardiac glands (lamina propria)
• Esophageal submucosal glands
• Smooth and striated muscle in musc. externa
• Mostly retroperitoneal except at lower part

Question 7

Esophageal sphincters

Answer 7

1. Upper: anatomical
2. Lower: physiological

Question 8

Esophagogastric junction features

Answer 8

Abrupt transition from SSNK to simple columnar at Z-line
Mucosa goes from smooth to plicated
2 layers of musc. externa becomes 3 layers

Question 9

Barrett’s esophagus

Answer 9

Metaplasia at Z-line due to esophageal irritation (e.g. GERD). SSNK -> simple columnar up the esophagus

Question 10

Stomach regions

Answer 10

1. Cardia
2. Fundus
3. Pylorus

Question 11

Cardiac stomach

Answer 11

Short cardiac glands, short pits. Mostly mucous cells, some parietal and chief cells

Question 12

Fundic stomach

Answer 12

Long, heterogenous gastric glands branched at bottom of pits

Question 13

Gastric gland/pit cells

Answer 13

Surface mucous cells
Deeper mucous neck cells
Eosinophilic parietal cells
Basophilic chief cells

Question 14

Pyloric stomach

Answer 14

Looks similar to cardiac stomach, deeper pits but short glands. Common ulcer/fissure region.

Question 15

Pyloric sphincter

Answer 15

Anatomical sphincter
Thickening of ICL; 3 layers of musc. externa becomes 2.