Gut Motility Flashcards
Name the plexus’ found in the gut wall
Sub-mucosal plexus (between the sub mucosa and the circular muscle layer) and the myenteric plexus (between the longitudinal and circular muscle layers)
What nervous system controls smooth muscles?
Enteric nervous system
What is the function of the interstitial cells of Cajal?
They mediate enteric neurotransmission
What are the pacemaker cells of the enteric nervous system?
The interstitial cells of Cajal
What does the enteric nervous system do?
Mediates reflex action in the absence of CNS input (a.k.a. During the interprandial period)
What influences the enteric nervous system?
Extrinsic factors
- Vagal control (excites non-sphincteric muscle)
- Sympathetic control (inhibits non-sphincteric muscle and excites sphincteric muscle)
What are the neurohormones that have an effect on the enteric nervous system?
5-hydroxylation-tryptamine (5-HT)
Motilin
Opioid receptor
Name two ways motility can be functionally measured.
Pressure - measuring circular muscle function
Transit - measuring how fast food passes out of the stomach
Describe scintigraphy.
This is when radiolabelled isotopes are swallowed, and the radiation produced is measured outside the body with a gamma camera
Name the nerve that supplies the striated muscle, on the upper third of the oesophagus.
The vagus nerve
What nerve allows motor functions of the smooth muscle of the oesophagus?
Parasympathetic branches of the vagus nerve
- this synapses with both the submucosal and myenteric plexus’
Where do the vasomotor sympathetic fibres that supply the oesophagus arise from?
T1-4/6
Name an oesophageal disorder that only affects striated muscle.
Polio
What problems can occur when the oesophageal smooth muscle stops working?
The transition of the bolus from the mouth to the stomach is affected
What is achalasia?
An oesophageal disorder that results in peristaltic failure, causing the LOS to remain contracted and eventually causes dilation of the oesophagus
How is achalasia treated?
- Dilation of the LOS with a ballon
- Myotomy (from the outside of the person)
What happens to the oesophagus in scleratoma?
The connective tissue under the mucosa thickens. The LOS becomes weak due to a constant low pressure. This, combined with an absence of peristalsis can cause severe oesophageal reflux and therefore oesophagitits
Describe nutcracker oesophagus.
This is a very high pressure in the oesophagus and causes pain on swallowing (though swallowing is functional)
It’s a benign prognosis
What is a diffuse oesophageal spasm?
When the peristalsis moves faster than the food
Name the four phases of the interprandial stage.
1) quiescense - a prolonged period
2) contractility frequency increases
3) peak electrical and mechanical activity
4) declining activity