Food propulsion

• Peristalsis: occurs from the top to the bottom of the stomach, forcing food past the pyloric sphincter
• Grinding: the pylorus allows about 3 ml of chyme into the small intestine at a time
• Retropulsion: peristaltic waves close the pyloric sphincter, forcing contents back to the stomach; the stomach empties in 4-6 hours
• Steps to food propulsion

  peristalsis

  grinding

  retropulsion