Pathophysiology of gastric disease Flashcards
What is GORD?
Gastro oesophageal reflux disease
What are the symptoms of GORD?
- Chest pain
- Acidic taste in mouth
- Cough
What kind of things will trigger GORD?
- Obesity
- Pregnancy
- Hiatus Hernia
- LOS function
- Delayed gastric emptying
What are some of the possible consequences of GORD?
- Nothing
- Oesophagitis
- Strictures → causes vomiting everytime you swallow
- Barret’s oesophagus→ metaplasia of oesphagus
What is Barret’s Oesophagus?
Metaplasia of the stratified squamous epithelia → simple columnar epithelia → can lead to an adenocarcinoma
What components make up to the Lower Oesophageal Sphincter?
- Muscular element
- Right crus of diaphragm (loops around oesophagus)
- Oesphagus angled entry to stomach
- Intra abdominal pressure
All act together to contract around the oesophagus
When is pressure around the LOS highest and lowest?
Highest at night
Lowest after meals
How would you treat someone with GORD?
- Lifestyle modification → eat slower, smaller meals, lose weight
-
Pharmacological
- Antacids → add a layer on top of the stomach
- H2 antagonists → stop parietal cell release of H+
- Proton Pump inhibitos
- Surgery - rare!
What is a hiatal hernia and how can this lead to GORD?
A hernia where part of the stomach slips above the diaphragm
Mechanism relating to GORD not fully understood:
- Loss of intra abdominal pressure creating basal tone
- Don’t get the increase in LOS tone when straining
What is Gastritis?
Inflammation of the protective lining of the stomach (stomach mucosa)
What symptoms might present if someones suffering with gastritis?
- pain
- nausea
- vomiting
- bleeding
What kind of things will cause acute gastritis?
- Heavy use of NSAIDs
- Lots of alcohol- dissolves mucus lining
- Chemotherapy
- Bile reflux into the stomach
Any chemical injury damages stomach epithelia and reduces mucus production. Mucosa responds by vasodilation/ oedema and inflmmatory cells
How do you treat acute gastritis?
Remove the stimulus
What is chronic gastris and how can it be divided?
Perisitant stomach inflammation
- Bacterial
- Autoimmune
Explain what happen in autoimmune gastritis and what some of the consequences can be
Autoantibodies are made to gastric parietal cells, affects the fundus but spares the antrum
- Can lead to pernicious anemia (B12 deficiency anaemia) as parietal cells produce intrici factor for B12 absorption and acid for iron absorption
- B12 deficiency can lead to glossitis
- Anorexia as painful to eat
- neurological symptoms
What is the most common cause of bacterial, chronic gastritis?
Heliobacter Pylori
Give some of the features of H. Pylori organism
- Helix, gram negative, microaerophilic
- Spread feaco-orally
- Produces urease → converts urea to ammonium and increases local pH
- Flagellum gives good motility and allows adhesion to mucus layer so remains in stomach
What problems does helicobacter pylori cause?
- Releases cytotoxins causing direct epithalial injury
- Expresses urease producing ammonia whic is toxic to epithelia
- Can degrade the mucus layer
- Promotes inflammatory response
How does the location of H. pylori affect the effect it has on the stomach?
Antrum colonisation only: affects G cells, increasing gastrin secretion. Increased parietal cell acid secretion
Can cause duodenal epithelial metaplasia and ulceration if colonises the duodenum
If in the antrum and body: effects cancel and the patient is asymptomatic
If predominantly in body: causes atrophy effect, stomach shrinks making breakdown and ulceration a lot easier → leads to intestinal metaplasia and potentially cancer
How would you diagnose Helicobacter pylori?
- Urea breath test using carbon 13
- Stool antigen test
- Can use upper GI endoscopy if needed
How would you treat a patient who has helicobacter pylori?
- Proton Pump inhibiotrs
- Amoxicillin + (clarithromycin or metronidazole)
Define Peptic ulcer disease
Defect in the gastric/ duodenal mucosa that extends through muscularis mucosa
Commonly affects lesser curve/ antrum of stomach and first part of duodenum
Compare and contrast gastric ulcers and duodenal ulcers based on:
incidence, age distribution, social class, blood group, acid evels and H.pylori gastritis
What are the normal defence mechanisms of the stomach?
- Mucus
- Bicarbonate
- Adequate mucosal blood flow to remove acid that diffuses through injured mucosa
- Prostaglandins
- Epithelial renewal
Why is the breakdown of normal stomach defences, more important than excessive acid in peptic ulcer disease?
Ulcers can develop in people with any level of acid; normal or low
Rpaid gastric emptying/ inadequare neutralisation from the bile/ pancreas is more implicated in duodenal ulcers
What things can cause mucosal injury, leading to peptic ulcer disease?
- H. Pylori
- NSAIDs
- Smoking (more involved in relapse than initial insult)
- Major physiological stress e.g. burns
Where do chronic peptic ulcers most frequently occur?
At mucosal junctions
e.g. where antrum meeds body and where antrum meets duodenum
Describe the morphology of peptic ulcers
- Generally <2cm
- Base of ulcer is necrotic/ granulation tissue
- Muscularis propria can be replaced by scar tissue
What are some of the clinical consequences of peptic ulcer disease?
- Narrowing of stomach due to repeated scar tissue
- Perforation causing peritonitis
- Erosion of adjacent structures (liver or pancreas)
- Heamorrhage
- Malignancy (rare)
Give some of the symptoms of peptic ulcer disease
- Epigastric pain, sometimes moving to the back
- burning/ gnawing
- pain often follows meal times
- pain often at night
What are some of the serious symptoms of peptic ulcer disease?
- Haematemesis (vomiting blood) or malaena (dark stools)
- Early satiety - from repeated scarring narrowing lumen
- Weight loss - as reluctant to eat
How do you manage someone with peptic ulcer disease?
- lifestyle modification- avoids foods making it worse
- Stop exacerbating medications
- Test for H. pylori and eradicate if present
- PPI’s
- Endoscopy
What is functional dyspepsia?
When someone present with the symptoms of ulcer disease but there is no physical evidence of organic disease
What is Zollinger- Ellison syndrome?
A non beta islet cell gastrin secreting tumour of the pancreas
Consequence:
- proliferation of parietal cells → lots of acid production
- Causes severe ulceration of stomach and small bowel
- Symtpoms of abdominal pain and diarrhoea
What is stress related mucosal damage?
Broad term to describe pathology attributed to acute, erosive, inflammatory insult to the upper GI tract associated with critical illness:
- Severe burns
- raised intracranial pressure
- sepsis
- severe trauma
- multiple organ failure
What are some of the featurs of stomach cancer?
Has to be quite a large cancer before symptoms present
- dysphagia
- loss of appetite
- malaena
- weight loss
- nausea/ vomiting
- Virchow’s nodes
What are some of the risk factors for developing stomach cancer?
- Male
- H. pylori
- Dietary factors
- Smoking
