🐭 RAT series
Points to Ponder for NEET-PG, FMGE & NEXT
- Gastrointestinal reflexes involve a complex interplay between the CNS, ENS, and GI peptides to regulate movement and secretion.
- The enterogastric reflex inhibits gastric emptying in response to acidic chyme in the duodenum or stomach.
- The gastrocolic reflex increases colonic motility and the urge to defecate after a meal.
- The gastroileal reflex complements the gastrocolic reflex by promoting defecation upon ileal emptying into the colon.
Regulation of Movement and Secretion
- GI reflexes work in conjunction with:
- Long reflexes: Originate from the central nervous system (CNS)
- Short reflexes: Governed by the enteric nervous system (ENS) within the GI tract
- GI peptides: Act as chemical messengers to coordinate activity
Types of GI Reflexes
Enterogastric Reflex
- Stimulus: Presence of acidic chyme in the duodenum (pH < 4.5) or stomach (pH < 1.5)
- Effect:
- Inhibits gastrin release from G cells in the stomach antrum
- Decreases gastric motility and acid (HCl) secretion
- Overall effect: Slows gastric emptying
Gastrocolic Reflex
- Stimulus:
- Distention of the stomach following a meal
- Byproducts of digestion reaching the small intestine
- Effect:
- Increases colonic motility (peristalsis)
- Urges defecation to make space for new food in the stomach
Gastroileal Reflex
- Stimulus: Opening of the ileocecal valve and passage of chyme from the ileum to the colon
- Effect:
- Stimulates colonic motility in coordination with the gastrocolic reflex
- Promotes defecation
Quiz
