Large Intestinal Motility
- Motility of the large intestine enhances exposure of luminal contents to the absorptive mucosa and facilitates its transports along the length of the colon. The large intestine displays both peristaltic and mixing patterns of contractions described in GI Motility Patterns.
- Roughly 2-3 times per day a large wave of peristaltic contraction, termed a 'Mass Movement', is initiated in the transverse colon and pushes a large bolus of feces into the rectum. 'Mass Movements' can be initiated by irritation of the large intestine mucosa or by distension of the stomach, explaining why an urge for defection often arises after food consumption, termed the "Gastrocolic Reflex".
- Defecation is initiated when feces enters the rectum and the internal anal sphincter reflexively relaxes. However, defection does not occur until the external anal sphincter, which is under voluntary control, is also relaxed.