Disease of the Small Intestine

Question 1

How is the following supplied to the small intestine: blood, innervation, and lymphatics?

Answer 1

• blood is supplied by the celiac and cranial mesenteric arteries –> drains to the liver via the portal veins
• Autonomic innervation = vagus and splanchnic nerves
• Lacteal drain into the mesenteric lymphatic vessels –> empties into the cisterna chyli

Question 2

What are the layers of the small intestine? Which layer is the most important clinically? Why?

Answer 2

3 layers = (inner) mucosa, submucosa, muscularis (outer longitudinal, inner circular) and seroa
- most important layer = mucosa
- mucosa = responsible for digestive, absorptive, and protective barrier

Question 3

What’s the major energy source for the small intestine?

Answer 3

glutamate

Question 4

How is feline cobalamin metabolism different than the dog?

Answer 4

Cats lack transcobalamin I (a binding protein) so can lose cobalamin via enterohepatic recycling –> can deplete its cobalamin storage within a month

Question 5

What’s the pacemaker cell in the small intestine?

Answer 5

interstitial cells of Cajal

Question 6

What are the 3 phases of small intestinal motility in the fasted state?

Answer 6

1. quiescent phase
2. minor contractile activity
3. short migrating myoelectric (motor) complexes (MMC)

Question 7

How does motilin and erythromycin effect SI motility?

Answer 7

MMC is induced by motilin, which can also be created by low dose of erythromycin

Question 8

What’s MAMPS?

Answer 8

microbe-associated molecular patterns

Question 9

What’s PRRs?

Answer 9

on the SI mucosa, there is pattern recognizing receptors, then can recognize the conserved elements of bacterial structure –> MAMPs

Question 10

What’s the function of TLR2, TLR4, TLR5, and NOD2?

Answer 10

This is part of the SI mucosal PRRs then can find microbes
TLR2 = lipopeptide
TLR 4 = lipopolysaccharide
TLR 5 = bacterial flagella protein (flagellin)
NOD2 = bacterial lipopolysaccharide