Flashcards in Met: PBL 3 (GORD/Heartburn) Deck (49)
Form of indigestion pain felt as a burning sensation in the chest, caused by acid regurgitation into the oesophagus from the stomach
What is helicobacter pylori?
An organism found in the stomach and duodenum of many people with peptic ulcers,
What is a urea breath test used to diagnose?
An individual has to drink a substance containing urea, if H. Pylori is present it has a urease enzyme that will convert the urea to carbon dioxide and nitrogen, the CO2 is then absorbed through the stomach into the blood, and therefore exhaled. Therefore, the individual is asked to breathe into a bag which is sent for lab testing to look for the quantities of CO2, if large this is indicative of H. Pylori infection
What is gastroparesis?
Where the stomach takes longer than normal to dispose of stomach acid
How may being pregnant increase your risk of acid reflux?
The change in hormone levels during pregnancy may weaken the LOS and the increased stomach pressure can push the gastric contents back up the oesophagus
Outline some of the risk factors for gastro-oesophageal reflux disease
Obesity (pressure on abdomen), eating lots of fatty food (takes longer to dispose of stomach acid), smoking/coffee/chocolate/alcohol (may relax LOS), hiatus hernia, stress, gastroparesis
Outline two medications which can lead to GORD symptoms
Calcium channel blockers (treat hypertension) and nitrates (treat angina) as these can relax the LOS
Outline four medications that can contribute to the development of oesophagitis
NSAIDs (includes ibuprofen), SSRIs (type of antidepressant), corticosteroids (treats severe inflammation), bisphosphonates (treat osteoporosis)
What is oesophagitis?
Where stomach acid irritates and inflames the lining of the oesophagus
What is the lower oesophageal sphincter (LOS)?
Ring of muscle at the bottom of the oesophagus which works as a valve to let food into your stomach to be digested by acid, and closes to prevent any acid leaking back up into the oesophagus
What is the cause of the symptoms associated with GORD?
The movement of acid back up into the oesophagus when the LOS has been weakened
Why is acid reflux proposed to be a vicious cycle?
Reflux can lead to scarring, and the scarring can cause damage to the LOS, leading to ability for more acid to move up the oesophagus, worsening the reflux/GORD each time
Define 'acid reflux'
Where acid is regurgitated into the throat or mouth, usually causing a sour taste at the top of the throat or back of the mouth
Name the treatments for GORD/acid reflux
antacids, H2 antagonists, PPIs
When may further investigations be required in someone who presents with symptoms of reflux?
If they have pain when they swallow, have difficulty swallowing OR when symptoms don't improve with medication
What is Barrett's oesophagus?
When the oesophageal epithelium undergoes metaplasia from stratified squamous to simple columnar and this increases the risk of oesophageal cancer largely
How can acid reflux lead to iron-deficiency or anaemia?
Can cause bleeding where the irritation or scarring is due to small blood vessels beneath being damaged, bleeding is in small amounts but these can lead to a level of iron-deficiency or anaemia due to blood loss here
What is the mechanism of alginates in the treatment of GORD?
They form a 'raft' that floats on the surface of the stomach contents and reduces reflux and protects the oesophageal mucosa
What are potential treatment options for dysphagia?
Surgery to wide oesophagus, diet changed to more liquid food, fed by tube, speech therapy to develop different swallowing techniques
Describe the mechanism of action of antacids in the treatment of reflux
Contain alkaline ions (e.g. calcium/magnesium carbonate) which chemically neutralise the stomach acid contents
Describe the mechanism of action of H2 receptor antagonists in reflux
Histamine binds to H2 receptors to cause acid production by parietal cells, so blocking this receptor reduces the stimulation of acid production so less gastric acid is secreted HOWEVER, doesn't stop acid secretion stimulated by the parasympathetic nervous system. This is used as a preventative medication
Describe the mechanism of action of proton pump inhibitors (PPIs) in reflux
Blocks the protein pump on the apical surface of parietal cells so prevent the production of acid entirely allowing the cells of the oesophagus to heal. They irreversibly bind to/block the H+/K+ ATPase or gastric proton pump on parietal cells
What hormones do endocrine cells secrete?
Gastrin and histamine
What is the role of gastrin and histamine in the stomach?
Stimulate acid production by binding to the basolateral surface of the parietal cells
What activates the secretion of acid from the gastric parietal cells?
Histamine, gastrin and parasympathetic response to the sight of food (cephalic response)
Describe how PPIs are administered to patients (inactive form)
Given in an inactive form which is lipophilic so it readily crosses cell membranes, and in an acidic environment the inactive drug becomes protonated and becomes active which then covalently, irreversibly binds to the gastric proton pump to deactivate it (prevent acid production)
What are the disadvantages of PPIs?
HCl is involved in the digestion of proteins and absorption of nutrients, especially vitamin B12 and calcium, and therefore a deficiency of HCl can cause malnutrition
Explain why antacids aren't a long-term solution for acid reflux?
They only neutralise the stomach acid and don't actually prevent the damage that the acid is doing to the oesophagus; doesn't correct the relaxation of the LOS
What are the potential consequences of having a helicobacter pylori infection of the stomach?
May cause GI conditions such as duodenal and gastric ulcers
Describe blood antibody testing for helicobacter pylori
Checks to see if body has made H. Pylori antibodies, so if they are present, you are either currently infected or have been in the past
Describe stool antigen testing for helicobacter pylori
Checks for H. Pylori antigens in the faeces
What 3 methods may be used to diagnose oesophagitis?
Upper endoscopy, biopsy, upper GI series
What are the symptoms of a helicobacter pylori infection?
Acute gastritis (stomach pain), nausea
How can a helicobacter pylori infection lead to damage of the stomach?
Flagella grip to GI epithelia and protects them from gastric acid (are within mucosa), then bury in stomach mucosa and break down urea (produced by protein breakdown by pepsin) via urease enzyme --> ammonia and carbon dioxide. Ammonia produced is toxic to epithelia and begins breaking down stomach epithelia IN SOME INDIVIDUALS
Does everyone with a helicobacter pylori infection experience symptoms?
No, up to 85% of those with infection have no symptoms or complications
How is a H. pylori infection treated?
Antibiotics and PPIs to kill the bacteria
Compare the epithelia at the gastro-oesophageal junction in a healthy individual
Oesophageal epithelia = stratified squamous
Gastric epithelia = simple columnar
Compare the epithelia at the gastro-oesophageal junction in an individual with acid reflux
There may be some scarring/burns at the G-O junction
Compare the epithelia at the gastro-oesophageal junction in an individual with Barrett's oesophagus
There is simple columnar metaplasia in the oesophagus
Name 4 anatomical features which prevent reflux
Contraction of crural diaphragm (pinch action at terminal oesophagus), viable LOS normally seals off stomach from oesophagus, enters cardia at an acute angle, terminal portion of the oesophagus is within the abdominal cavity
Describe the histology of the gastro-oesophageal junction in someone with GORD
Oedema, leukocyte invasion, thinning of squamous layer, dysplasia, goblet cell intestinal metaplasia
What substances are mainly secreted in the cardia of the stomach?
Mucus (mucous neck cells)
What substances are mainly secreted in the fundus and body of the stomach?
Mucus (MNCs), HCl (parietal cells), pepsinogen (chief cells), histamine (endocrine cells)
What substances are mainly secreted in the pylorus of the stomach?
Mucus (MNCs), histamine and gastrin (endocrine cells)
What causes the pain of heartburn?
Heartburn pain occurs when afferent nerves in the oesophageal wall are activated by the presence of luminal acid; the acid moves through the epithelium of the oesophagus and activates receptors that generate a signal via spinal and vagal fibres to the central nervous system to cause the presentation of pain
How is heartburn distinguished from oesophagitis?
Oesophagitis is inflammation of the oesophageal mucosa caused by frequent reflux of the stomach contents, whereas heartburn is merely the pain phenotype when there is acid reflux into the oesophagus
How would oesophagitis be ruled out in a GORD diagnosis?
If there is no abnormality of the oesophagus in histology,, gross anatomy or upper GI series - if there was oesophagitis there would be constrictions and abnormalities of the oesophagus that are visible