Lecture 20 : Enteric Nervous System

Question 1

What is the enteric nervous system

Answer 1

Division of the autonomic nervous system controlling GI tract

Also known as the ‘little brain’

Question 2

What is the intramural plexus?

(intramural = within wall)
(plexus = nerwork of nerve fibres)

Answer 2

Consists of 2 plexuses :

Myenteric plexus (auerbach)
- controls motility, ie. Muscle contraction
- Full length of GI tract

Submucosal plexus (meissner)
- controls secretion, blood flow and absorption
- Stomach and intestines only

Question 3

What is the function of the enteric nervous system

Answer 3

Regulates digestion via…
- Motility
- Blood flow
- Enzyme secretion
- Other secretions

Can function separately to the CNS but can communicate via sympathetic and parasympathetic systems

Question 4

Main neurotransmitters :

Answer 4

• Noradrenaline
• ACh
• Serotonin
• Dopamine
• Nitric Oxide

Question 5

What is a short reflex and long reflex

Answer 5

Short reflex occurs only within the enteric nervous system without involving the brain or spinal cord.

Long reflex involves CNS.

Question 6

Diseases assocaited with ENS

Answer 6

Chaga’s Disease
- Neurones killed by toxin

Achalasia
- Lower esophagus fails to contract, peristalsis in esophagus is absent
- Due to loss of enteric neurones
- Difficulty swallong, chest pain, food retention in esophagus

Hirschprung’s Disease (megacolon)
- Cogenital absence of ENS neurones in colon
- happens soon after birth
- No presistalsis
- Severe constipation / obstruction

Distension
- Stretching of intestine because of buildup of shit or gas
- Bloating, pain

Colitis
- Inflammation of colon
- Diarrhea, bleeding
- Autoimmune or infection

Parkinsons
- Enteric neurones degenerate

Question 7

Peristalsis

Answer 7

Peristalsis is a coordinated, wave-like muscle contraction that moves food through the digestive tract.

It involves circular and longitudinal muscles, controlled by the enteric nervous system, and occurs from the esophagus to the rectum