Small Intestine Anatomy

Question 1

What are the three portions of the small intestine?

Answer 1

• Duodenum
• Jejunum
• Ileum

Question 2

Spiral folds that consist of mucosa and submucosa?

Answer 2

Plicae circularis

Question 3

Lymphoid aggregates in the submucosa?

Answer 3

Peyer’s patches

Question 4

What are the two plexi of the small intestine?

Answer 4

• Myenteric Nerve Plexus of Auerbach (Both layers of muscularis)
• Meissner Plexus (Submucosa)

Question 5

What is a major defense mechanism used by the small gut to neutralize food antigens and bacteria?

Answer 5

Secretory IgA

Question 6

What are Peyer’s patches composed of?

Answer 6

MALTs (Mucous associated lymphoid tissue)

Question 7

Name for the actin microfilaments under the microvilli in the small intestine?

Answer 7

Terminal web

Question 8

How do amino acids enter the body? Polysaccharides? Triglycerides?

Answer 8

• AAs - pancreatic proteases and then absorption into the caps
• Polysaccharides - Pancreatic enzymes
• TGs are broken down by pancreatic lipase, mixed with bile salts, absorbed into the epithelium and transferred into the body via the lymphatics

Question 9

Job of the paneth cells? Secretions?

Answer 9

Mucosal defense; Crypt defensins, CD95 ligand

Question 10

Function of the goblet cells?

Answer 10

Secrete gel forming mucins

Question 11

Function of the undifferentiated cells?

Answer 11

Function as reserve cells from which all other mucosal cells are renewed

Question 12

What contributes to small intestine sensitivity to chemoTx and RTx?

Answer 12

Mucosal epithelium of small intestine is replaced every 4-7 days