Gastric Digestion

• Parts of the stomach

  • Cardiac
  • Fundus
  • Pylorus
• Secretion and composition of gastric juice

  1. Secretion

  2. Composition
• Action of gastric digestive enzymes and the end products

  1. Action

  2. End products
• Nervous and hormonal control of gastric digestion

  1. Nervous control

  2. Hormonal control
• Gastric emptying


  1. Bolus enters stomach

  2. Bolus presses against stomach wall

  3. Pressure/stretch receptors stimulated

  4. Nerve impulses conducted to plexi

  5. Plexi send impulses to glands/muscles

  6. Increased gastric juice secretion

  7. Increased gastric motility

  8. Fatty chyme stimulates G cells to secrete gastrin

  9. Gastrin increases gastric juice secretion/motility

  10. Fatty chyme in duodenum stimulates secretin, pancreozymin, cholecystokinin

  11. Decreased gastrin/gastric juice inhibits gastric digestion
• Salivary amylase


  Little/no action in stomach (too acidic)
• HCl


  Produced by oxyntic cells, pH 1.5-2.5 (very acid)
• Pepsinogen


  Produced by peptic cells, converted to active pepsin by low pH and chloride ions
• Pepsin


  Hydrolyses proteins to smaller proteoses and peptones
• Lipase


  Converts triglycerides to smaller diglycerides and monoglycerides (free fatty acids and dextrins)
• Pregastric lipase


  Converts triglycerides to smaller diglycerides and monoglycerides (free fatty acids and dextrins)
• Gastric juice


  Mucus + enzymes + HCl
• Gastric motility and emptying