Upper GI Tract Flashcards
What is the angle of His and what does it contribute to the LOS?
The angle between the abdominal stomach and the fundus of the stomach
It prevents reflux
How does the diaphragm contribute to the efficacy of the LOS?
The left and right crux of the diaphragm contract against the sphincter to help its efficacy
What ligament allows the diaphragm and LOS to move independently of each other?
Phrenoesophageal ligament
What are the stages of swallowing?
Stage 0: Oral phase
Stage 1: Pharynx phase
Stage 2: Upper oesophageal phase
Stage 3: Lower oesophageal phase
What is manometry and its units?
A test to measure the motility and muscle contractions of the oesophagus
in mmHg
What is the usual manometry value for peristaltic waves?
around 40 mmHg
What is the resting pressure of the LOS?
around 20 mmHg
What is the role of the noncholinergic noradrenergic neurones (NCNA) of the myenteric plexus?
They mediate the decrease of LOS pressure (to <5 mmHg) during receptive relaxation
They are inhibitory neurones
What is receptive relaxation?
The Vagus nerve is activated when food is swallowed and relaxes stomach muscle to prepare for bolus.
What is the state of the oesophageal sphincters during stage 0 of swallowing?
Both oesophageal sphincters are constricted
What is the state of the oesophageal sphincters during stage 1 of swallowing?
Upper oesophageal sphincter opens on reflex
LOS is opened by the receptive relaxation reflex
What is the state of the oesophageal sphincters during stage 2 of swallowing?
Upper sphincter closes
What is the state of the oesophageal sphincters during stage 3 of swallowing?
Lower sphincter closes as food passes through
What happens to the muscles during stage 2 of swallowing?
Peristalsis:
Superior circular muscle rings contract
Inferior circular muscle rings dilate
Longitudinal muscles contract sequentially - (act antagonistically, contracting ahead of the bolus)
What is the effect of cholinergic fibres on sphincters?
Increase contraction of sphincter - exciting shortening of fibres
What causes Achalasia?
A loss of ganglionic cells in Aurebach’s myenteric plexus.
Decreased activity of inhibitory NCNA neurones
LOS remains constricted
What is Achalasia?
Hypermotility of oesophageal muscles
What are the causes of Achalasia?
Primary - aetiology unknown
Secondary -
Chagas’ Disease
Protozoa infection
Amyloid/Sarcoma/Eosinophilic Oesophagitis
How does Achalasia affect oesophageal motility?
Increases resting pressure of the LOS (pressure in LOS much higher than in stomach)
Delay in receptive relaxation and decrease in effect
Increased pressure in oesophagus caused by collection of swallowed food
Propagation of peristaltic waves ceases
What are the symptoms of Achalasia?
weight loss
dysphagia
regurgitation
retrostomach pain
What is Chagas’ disease
Infection by a parasite (Trypanosoma cruzi) that causes damage to the heart, oesophagus and other digestive tracts
What is Amyloid Oesophagitis?
Deposits of amyloid in the oesophagus (in the submucosa), puts pressure on and causes destruction of surrounding cells
What is Sarcoma Oesophagitis?
A form of malignant neoplasm arising from the oesophagus
What is the pathophysiology of Chagas’ disease?
The parasite damages the oesophageal myenteric plexus, causing:
- loss of esophageal peristalsis
- partial or absent lower esophageal sphincter relaxation
- megaesophagus - secondary oesophageal achalasia
What is the pathophysiology of Chagas’ disease?
The parasite damages the oesophageal myenteric plexus, causing:
- loss of oesophageal peristalsis
- partial or absent lower oesophageal sphincter relaxation
- megaoesophagus - secondary oesophageal achalasia