GI transport + GI Problems and Pharmacological solutions - NERVOUS SYSTEM

Question 1

What is the enteric nervous system and where is it found?

Answer 1

It is the digestive system’s own local neuronal complex.

Lies entirely within in the gut

Question 2

What part of the nervous system is the enteric nervous system part off?

Answer 2

Contains 100 million neurones

It is a sub-branch of the ANS, containing both sympathetic and parasympathetic nervous control

Question 3

What are the major functions of the enteric nervous system?

Answer 3

Major functions:

Control of motility

Regulation of blood flow

Regulation of gastric and pancreatic secretions

Regulation of GI endocrine cells

Defence reactions

Question 4

In general, what does the sympathetic nervous system control?

Answer 4

Sympathetic nervous control (NA):

Inhibition of GI secretions

Inhibition of motor activity

Contraction of sphincters

Contraction of blood vessels

Question 5

In general, what does the parasympathetic nervous system control

Answer 5

Parasympathetic nervous control (ACh):

Promotion of GI secretions

Promotion of motor activity

Relaxation of sphincters

Relaxation of blood vessels

Question 6

What is the ENS divided into?

Answer 6

The ENS can be split into two plexuses:

1. Myenteric plexus (aka Auerbach’s
   plexus)
   - located between longitudinal and circular layer of
   muscles.
   - Its main function is to control digestive tract motility.

Most prominent plexus
• Cholinergic innervation ↑ gastric motility and secretion
• Adrenergic stimulation ↓ gastric motility and secretion

2. Submucosa plexus (Meissner’s)-
   - Located within the submucosa of the intestinal wall
   - Its primary role is sensory- senses changes within the
   lumen
   - It regulating GI blood flow and controlling epithelial
   cell function