Motility and Regulation (Peristalsis, Hormones) - Anatomy and Physiology
- Which hormone released by the duodenum in response to fats and proteins stimulates gallbladder contraction?
- Cholecystokinin (CCK). It also stimulates pancreatic enzyme secretion and slows gastric emptying.
- What is the enterogastric reflex?
- Distension, acid or fat in the duodenum inhibits gastric motility and emptying, so the small intestine is not overloaded.
- Which enteric nerve plexus mainly controls GI motility?
- The myenteric (Auerbach) plexus, located between the circular and longitudinal muscle layers.
- How does parasympathetic (vagal) stimulation affect GI motility and secretion?
- It increases both. Sympathetic stimulation generally decreases motility and secretion.
- What is segmentation in the small intestine?
- Rhythmic contraction of nonadjacent segments of circular muscle that mixes chyme with secretions, with little forward movement.
- Which enteric nerve plexus mainly regulates glandular secretion and local blood flow?
- The submucosal (Meissner) plexus, located in the submucosa.
- Which hormone from stomach G cells stimulates gastric acid secretion and gastric motility?
- Gastrin.
- Which cells act as pacemakers that generate the slow waves of GI smooth muscle?
- The interstitial cells of Cajal.
- What is peristalsis?
- Waves of alternating contraction and relaxation of the muscularis that propel contents along the digestive tract.
- What is the gastrocolic reflex?
- Food entering the stomach triggers mass movements in the colon, often producing an urge to defecate after a meal.
- What is the migrating motor complex, and when does it occur?
- A cycle of strong contractions during fasting that sweeps undigested residue and bacteria from the small intestine toward the colon.
- Which hormone released by the duodenum in response to acid stimulates bicarbonate-rich pancreatic secretion?
- Secretin. The bicarbonate neutralizes acidic chyme entering the duodenum.