Gastro - Upper GI tract Flashcards
What are the 4 stages of swallowing and describe what happens at each stage?
Stage 0 - oral phase:
- Chewing and saliva prepare bolus - Both oesophageal sphincters are constricted
Stage 1 - Pharyngeal phase:
- Pharyngeal musculature guids food bolus towards oesophagus - Upper oesophageal sphincter opens - LOS opened by vasovagal reflex
Stage 2 - Upper oesophageal phase:
- Upper sphincter closes - Superior circular muscle rings contract & inferior rings dilate
Stage 3 - Lower oesophageal phase:
- Lower sphincter closes as bolus passes through
What is the effect of a functional disorder of the oesophagus?
Absence of a stricture - dysphagia
What are the causes of functional disorders of the oesophagus?
Abnormal oesophageal contraction:
- Hypermotility
- Hypomotility
- Disordered coordination
Failure of protective mechanisms for reflux:
- GastroOesophageal reflux disease (GORD)
What is dysphagia?
Difficulty swallowing
What is odynophagia?
Pain on swallowing
What is regurgitation?
Return of oesophageal contents from above an obstruction
What is reflux?
Passive return of gastroduodenal contents to mouth
Describe the mechanism of achalasia?
- Loss of ganglion cells in Aurebach’s myenteric plexus in LOS wall
- This leads to reduced activity of inhibitory NCNA neurones
- This means the LOS cannot relax/dilate
Describe pneumatic dilatation
- A pneumatic dilator is placed in the oesophagus
- A balloon is then placed in the LOS and is inflated
- Once complete inflation has occurred, everything is removed and flow is restored in the oesophagus
What is a Heller’s myotomy?
A surgical procedure:
cut the muscle 6cm on the oesophagus and 3cm onto the stomach to remove the stricture then wrap the fundus of the stomach around the exposed mucosa
What is a peroral endoscopic myotomy?
- A muscosal incision in made on the inisde of the oesophagus
- The creation of a submucosal tunnel occurrs
- Then a myotomy occurs, where as much muscle required, is removed
- Then the mucosal incision is closed up endoscopically
How does hypomotility occurr?
Neuronal defects result in muscle atrophy of oesophagus, therefore no peristalsis in smooth muscle and hence hypomotility - sphincter pressure is too low
Describe disordered coordination of the oesophagus
- Incooardinate contractions of the ring muscles in the oesophagus results in corkscrew oesophagus
What vascular anomalies can cause dysphagia and why?
Dysphagia Lusoria:
- Abberant right subclavian artery wraps around behind the oesophagus
- This applies pressure on it and makes it hard to swallow
Double aortic arch:
- The presence of a left and right arch that form a loop around the oesophagus can result in pressure making it difficult to swallow
What is the primary management for oesophageal perforations?
Initial:
- NBM
- IV fluids
- Broad sprectrum antibiotics and antifungals
- ITU/HDU level care
- Bloods
Surgical emergency
What is an oesophagectomy ?
When the main oesophagus is removed and the stomach is stretched and attached to the first viable part of the oesophagus
Describe a sliding hiatus hernia
Part of the stomach pushes through the diaphragm
State and describe the different types of gastritis
- Erosive and haemorrhagic gastritits:
- Acute ulcer - gastric bleeding and perforation
- Nonerosive, chronic active gastritis:
- Antrum
- Infection from helicobacter pylori
- Atrophic (fundal gland) gastritis:
- Fundus
- Autoantibodies destroy parts of pairetal cells and products of them, causing parietal cell atrophy
- This results in lower acid levels which can result in G cell hyperplasia and potentially cancer
- Reactive gastritis
How is gastric secretion regulated?
Stimulation:
- Neural:
- ACh: postganglionic transmitter of vagal parasympathetic fibres
- Endocrine:
- Gastrin (G cells of antrum)
- Paracrine:
- Histamine (ECL cells and mast cells of gastric wall)
Inhibition:
- Endocrine:
- Secretin (small intestine)
- Paracrine:
- Somatostatin (SIH)
- Paracrine & autocrine:
- PGs (E2 & I2), TGF-alpha & adenosine
How is mucosal protection acheived?
- Mucus film :
- Produced by epithelium
- Protective barier
- Bicarbonate secretion:
- Produced by prostaglandins
- Maintain pH
- Epithelial barrier:
- Apical layer is strong
- Can expel H+ ions
- Mucosal blood perfusion:
- Good blood supply
- Can easily remove H+ ions
What can occur during epithelial repair and wound healing?
Rapid restitution through migration:
- The endothelial cells can flatten and spread across the area of damage/exposure
Can cover defect through cell division
If basement membrane is destroyed:
- Acute wound healing required through normal healing cascade of white cells
How does H. Pylori affect the stomach?
The bacteria produced urease which converts urea and H20 into CO2 and NH3 which neutralises gastric acid
What are the treatments for ulcers?
PPI’s (Proton pump inhibitors)
H2 blockers
Surgery in extreme cases
