Gastric acid secretion, ulcers and GORD

• What is the primary secretion discussed in the study material?

  HCl (hydrochloric acid)
• What is the typical pH range of gastric acid?

  ~2-3
• How does HCl aid in digestion?

  It aids food digestion for optimal pepsin activity.
• What is the result of optimal digestion in the stomach?

  It enhances nutrient absorption and overall digestive efficiency.
• Which cells are responsible for producing HCl?

  Parietal cells
• What role does HCl play in the stomach's defense mechanism?

  It acts as a bactericidal agent that kills germs.
• How is the H+/K+ balance reversed in the stomach?

  It is reversed by Na+/K+ ATPase.
• What drives the secretion of gastric acid?

  • Neuronal pathways
  • Hormonal pathways
  • Activation of parietal cell H2 receptors
• What is the process of HCl formation in the stomach?

  1. CO2 diffuses from blood into stomach cells.
  2. CO2 combines with H2O to form H2CO3.
  3. H2CO3 dissociates into bicarbonate (HCO3-) and H+.
  4. H+ is secreted into the lumen in exchange for K+ via H+/K+ ATPase.
  5. HCO3- is secreted into plasma in exchange for Cl- (chloride shift).
  6. Cl- is transported into the lumen through ion channels.
  7. H+ and Cl- combine to form HCl.
• Which hormone is involved in acid secretion and released by enterochromaffin-like cells?


  Histamine
• What activates acid secretion in parietal cells?

  Activation of parietal cell H2 receptors.
• What role do muscarinic pathways play in gastric acid secretion?

  They act synergistically on parietal cells.
• What are the steps involved in the stimulation of parietal cells?

  1. Ach from nerves acts on M3 receptors.
  2. Histamine from ECL cells acts on receptors and stimulates H+/K+ ATPase activity.
  3. Gastrin from G cells acts on cholecystokinin receptors.
  4. PGE2 inhibits HCl release from parietal cells.
• What inhibits HCl secretion in animals?

  It is inhibited by being fed.
• What reflexes are involved in the inhibition of HCl secretion?

  Reflex M3 and G cells.
• How do G cells respond to foodstuffs?

  They are directly responsive to foodstuffs.
• What percentage of the population is affected by peptic ulcers?

  Approximately 10%
• What is Helicobacter pylori associated with?

  It is associated with peptic ulcers and chronic smoking.
• How does H. pylori damage the stomach lining?

  It damages the protective mucus layer.
• What condition is characterized by the reflux of stomach contents into the esophagus?

  Gastroesophageal reflux disease (GERD)
• What is the relationship between H. pylori and stomach cancer risk?

  1. pylori is strongly associated with ulceration and stomach cancer risk.
• What are the treatments for H. pylori infection?

  • Amoxicillin
  • Metronidazole
  • Clarithromycin
  • Bismuth chelate
• How do antacids work in treating gastric acid issues?

  • They neutralize gastric acid.
  • Usually contain HCO₃⁻, CO₃²⁻, OH⁻.
  • Bind H⁺ ions to reduce acidity.
• What are the methods to inhibit acid secretion?

  1. Anticholinergic agents (M₃ antagonists)
  2. Cholecystokinin receptor antagonists
  3. Proton pump inhibitors (PPIs)
• What is a significant interaction of omeprazole?

  It inhibits CYP450 (CYP2C19).
• What is the function of Sucralfate in ulcer treatment?

  • Forms a viscous paste at ulcer sites.
  • Stimulates mucus and prostaglandin production.
  • Enhances absorption of therapeutic agents.
• How do NSAIDs affect gastric health?

  They block PG production, increasing gastric ulceration risk.
• What is achlorhydria?

  No HCl production in the stomach.
• What can cause achlorhydria?

  Medications, gastric bypass surgery, or stomach cancer.
• What is a consequence of achlorhydria?

  It increases pepsin activity and causes digestive issues.