s2-L20-The enteric nervous system

Question 1

What is enteric nervous system?

Answer 1

• 3rd division of the ANS
• intrinsic innervation of the GI tract
• network of neurons(80-100 million)

Question 2

Where is enteric nervous system located?

Answer 2

• Located in two major plexuses of ganglion cells and their fibre bundles
  1.Submucosal (Meissner’s) plexus
  2.Myenteric (Auerbach’s) plexus

Question 3

What are the layers of the enteric nervous system ?

Answer 3

Longitudinal muscle
👇
circular muscle
👇
submucosa
👇
mucosa
👇
lumen

Question 4

Name the types of neurons found in the enteric nervous system

Answer 4

-afferent (sensory) neurons

-Interneurons

-Efferent (secretomotor) neurones:-
1.Excitatory or inhibitory
2. many NTMs

-Effectors
1.Motor and secretory

Question 5

What does the enteric nervous system do ?

Answer 5

• controls motility
• secretory reflex - submucosal plexus
• blood flow
• motor reflex - myenteric plexus(ENS)

Question 6

What does the ENS do with the CNS ?

Answer 6

-integration with CNS
ENS <-> SNS/PNS <-> CNS
-CNS influence varies along GIT (gastrointestinal tract)

Question 7

Name diseases/dysfunction associated with ENS.

Answer 7

• Age
  -Disease >Pathology >ENS specific > NS more generally
  -Function
• Chaga’s disease - The parasite affects both excitatory and inhibitory neurones in the ENS, leading to oesophageal dilation.
• Achalasia - there is a selective loss of inhibitory neurons causing failure of the lower oesophageal sphincter to relax.
• Hirschsprung’s disease
• Congenital absence of ENS neurones
• Peristaltic wave halts at the section missing ENS neurones
• Abolition of rectoanal reflex

Question 8

What are some common disease are associated with it?

Answer 8

General neurological conditions:
-Parkinson’s disease
-Peripheral neuropathies
-Myasthenia Gravis

Irritable bowel syndrome (IBS)