Gastrointestinal Tract
Motility Small Intestine and Large Intestine Motility
• Intestinal slow waves: Segmentation and peristalsis
• Regional motility
• Ileocecal sphincter
• Periods of segmentation are followed by brief period of peristalsis allowing:
i. INTERSPACED MOVEMENT - propulsion then mixing/distribution to
facilitate optimal digestion and absorption
ii. (up to 12/min in duodenum and upper jejunum to ~8/min at the terminal
ileum)
• BOTH CAN BE ALTERED BY ENS, AUTONOMIC NERVOUS SYSTEM, HORMONES
• SEGMENTATION = main pattern of SI in the small intestine
• Is TRIGGERED by PACEMAKER - rhythm will vary in the region of SI- there are more food bolus in duodenum
than ileum - all motility is much reduced
• FREQUENCY GRADIENT of RHYTHMIC CONTRACTIONS in the SI promotes aboral propulsion of the intestinal
chyme
• DISTENSION = primary STIMULUS via enteric nervous system
Integration of Physiological Systems Page 1
Motility Small Intestine and Large Intestine Motility
• Intestinal slow waves: Segmentation and peristalsis
• Regional motility
• Ileocecal sphincter
• Periods of segmentation are followed by brief period of peristalsis allowing:
i. INTERSPACED MOVEMENT - propulsion then mixing/distribution to
facilitate optimal digestion and absorption
ii. (up to 12/min in duodenum and upper jejunum to ~8/min at the terminal
ileum)
• BOTH CAN BE ALTERED BY ENS, AUTONOMIC NERVOUS SYSTEM, HORMONES
• SEGMENTATION = main pattern of SI in the small intestine
• Is TRIGGERED by PACEMAKER - rhythm will vary in the region of SI- there are more food bolus in duodenum
than ileum - all motility is much reduced
• FREQUENCY GRADIENT of RHYTHMIC CONTRACTIONS in the SI promotes aboral propulsion of the intestinal
chyme
• DISTENSION = primary STIMULUS via enteric nervous system
Integration of Physiological Systems Page 1
