Gastro

Question 1

Layers of GI mucosa

Answer 1

Outermost
Adventitia/Serosa (connective tissue)
Muscularis Externa (contains outer longtitudinal muscle layer, Auerbach’s (myenterix) plexus, inner circular muscle layer)
Submucosa (blood vessels, lymphatics, Meissner’s (submucosal) plexus)
Inner mucosa (split into outer muscular layer (muscularis interna), Lamina propria and inner epithelial layer)
Innermost (in contact with food)

Question 2

Gastric mucosa and secretory cells

Answer 2

• Cells dive deep into lamina propria to create gastric pits, which function as glands
• G cells: secrete gastric
• Parietal cells: secrete HCl
• Chief cells: secrete pepsinogen
• Foveolar (surface mucous) cells: secrete mucous (contains water, glycoproteins and HCO3-)

Question 3

GORD pathophysiology

Answer 3

• Normal tone of lower oesophageal sphincter (LOS) is 10-45 mmHg
• In GORD, there is reduced tone and gastric acid moves into the oesophagus, causing the pH on the oesophagus to drop below 4
• Repeated acid becomes pathological and causes inflammation and scarring which can lead to stricture formation (oesophageal stenosis)

Question 4

Barrett’s oesophagus pathophysiology

Answer 4

• Prolonged GORD leads to pathological dysplasia (or metaplasia) of the normal oesophageal stratified squamous epithelium into intestinal columnar epithelium (which is better at dealing with acid)

Question 5

GORD symptoms

Answer 5

• Pyrosis (heartburn)
• Cough
• Hoarse voice
• Regurgitation (undigested food and gastric acid)
• Dysphagia
• If acid reaches pharynx/larynx: pharyngitis or asthma

Question 6

GORD risk factors

Answer 6

• Obesity
• Smoking
• Alcohol excess
• Spicy/fatty food intake
• Stress
• Hiatus hernia
• Zollinger Ellison syndrome
• Scleroderma

Question 7

GORD investigation

Answer 7

• Can trial PPI and check for symptom control
• Gold standard: 24h oesophageal pH monitoring
• Barium swallow: to look for structures
• Endoscopy + biopsy if worried about Barrett’s oesophagus

Question 8

GORD management

Answer 8

• Lifestyle changes (weight loss, avoiding spicy/fatty food, propping up in bed)
• Antacids (symptom relief)
• PPIs (e.g omeprazole, lansoprazole) or H2-receptor antagonists (e.g cimetidine, ranitidine)
• Prokinetics (to increase lower oesophageal sphincter (LOS) tone)
• Baclofen (reduces transient relaxation of LOS)
• Surgery (for refractory cases, usually Nissan fundoplication - fundus of stomach wrapped and tightened around LOS)