CSIM 1.50: Gastrointestinal Inflammation Flashcards
What is secreted at the stomach?
- Acid
- Pepsinogen
- Intrinsic factor (B12 absorption)
Which cells;
1) secrete acid?
2) secrete pepsinogen?
3) Secrete intrinsic factor?
1) Parietal cells
2) Chief cells
3) Parietal cells
What can cause acute gastritis?
ABC: • Autoimmune • Bacterial (H. pylori) • Chemical • Vascular damage • Alcohol
What are the symptoms of acute gastritis?
- Abdominal pain
* Vomiting/Haematemesis
What are the chemical causes of acute gastritis?
- Bile and bicarbonate reflux into the stomach
- Disorganised motility
- Gallstones
What condition is associated with autoimmune gastritis? Why?
Associated with macrocytic (PERNICIOUS) anaemia
• Parietal cells damaged
• No intrinsic factor produced
• B12 cannot be absorbed
• Macrocytic anaemia as the cell grows but DNA cannot replicate
What does H. pylori secrete to protect it from the harsh environment of the gut?
- Urease
* Phospholipase
How is the damage to the mucosa caused in bacterial gastritis?
- Toxins produced by the bacteria
* Lymphocytes and polymorphs from the host immune response damage the mucosa
Describe the progression of gastritis regardless of cause, if left untreated
Chronic gastritis leads to ATROPHIC GASTRITIS:
- Atrophy occurs, where parietal cells die, and fibrosis occurs
- Digestion is impaired, as there is a loss of H+ and intrinsic factor secretion (parietal cells)
- The gastric epithelium undergoes intestinal metaplasia due to the change in microenvironment
- ECL cells undergo hyperplasia, which lead to a carcinoid tumour
Describe the metaplasia seen in chronic gastritis
Gastric cells become:
• Small bowel cells first (absorptive)
• Then colonic
What is ulceration? What is the commonest cause when found in the:
1) Upper GI?
2) Small bowel?
3) Colon?
How does ulceration differ from erosion?
A breach in the mucosa which extends through the muscularis mucosa into the submucoa+
1) Peptic ulceration
2) Crohn’s disease
3) Ulcerative colitis
Erosion constitutes damage to the muscularis mucosa only (far more superficial)
What causes acute peptic ulceration?
- Chemical injury
- Severe stress
NB: NOT H. pylori, as this can only cause ulceration chronically
What are the major complications associated with ulcers?
- Haemorrhage (20%)
- Perforation of adjacent organs (perforates into the liver)
- Stenosis and stricture of lumen due to fibrosis (IMG 120)
Where are peptic ulcers found?
- Antrum of stomach
* First part of duodenum
What is Zollinger Ellison syndrome?
Gastrin-producing tumours, which can cause peptic ulcers
Describe the histology of an ulcer
From superficial to deep:
• Top layer of exudate and necrotic tissue
• Granulation tissue (inflammed, vascular repair tissue)
• Fibrous tissue
IMG 118
What causes chronic oesophagitis?
Reflux due to: • Defective LOS • Hiatus hernia • Gastric surgery Other rare causes: • Crohn's disease • TB
Describe the morphological changes seen in chronic reflux oesophagitis
- Basal cell hyperplasia
- Elongation of papillae
- Lymphocytes and eosinophils in the epithelium
What are the complications of chronic oesophagitis?
- Haemorrhage
- Perforation
- Fibrosis and stricture
- Barrett’s oesophagus
What is visible in Barrett’s oesophagus?
- Squamo-columnar junction
- Gastro-oesophagal junction
IMG 119
How do patients with Crohn’s disease present?
- abdominal pain
- fever
- diarrhoea
Where does Crohn’s affect and what pattern is seen?
Usually the colon, but can be any part of the GI tract from mouth to anus -
The inflammation is:
• DISCONTINUOUS/PATCHY
• Transmural (all the way through when viewed in cross section- not just lumen)
• Fissuring ulceration
What is the most common inflammation seen in Crohn’s?
Terminal ileitis
How is Crohn’s disease differentiated from ulcerative colitis?
- UC only seen in colon
- Granuloma seen in Crohn’s
- Discontinuous and transmural inflammation in Crohn’s with fissuring ulceration
- UC does not lead to strictures
What are the complications of Crohn’s?
- Fistulae (bowel, skin, bladder, vagina)
- Loss of protein
- Malabsorption
- Bowel cancer
How does ulcerative colitis present?
• Bloody diarrhoea
What gene is associated with Crohn’s disease?
NOD 2 gene
Describe the pattern/distribution of UC
- Distal colon
- Uniform (not patchy, continuous)
- Confined to lamina propria mucosa (not transmural)
- Glands destroyed
NB: in severe cases, can cause backwash ileitis
Describe the acute and chronic phase of ulcerative colitis
Acute phase:
• Red and friable
• Ulcerations
• Pseudopolyps (undermining ulceration, causing a ‘mushroom’) IMG 121
Chronic phase:
• Shortening of colon
• Loss of normal mucosal folda
What happens to the vasculature in UC?
It becomes congested
What are the main complications of UC?
- Toxic megacolon
* Polyps (dysplasia -> malignancy)
