Movement of the Large Intestine


Mixing movement (haustration)

This movement is almost similar to the segmentary movements which occur in the small intestine large circular contractions occur in the large intestine in which a zone of 2.5cm of circular and longitudinal muscles contract at the stimulated point. At the same time, the unstimulated portion bulges outward to form a bag_ like sacs known as haustrations the haustral contractions once initiated usually reach peak intensity in about 30 sec and disappear for the next 60 sec.


Peristalsis

This is a progressive contractile wave proceeded by a wave of relaxation which occurs in the large intestine/colon as elsewhere in the gut. Peristalsis like segmentation contractions moves the chyme slowly 4.5cm/hours along the colon. It takes 45-48hours for the chyme to travel the entire length of the colon.


Propulsive movements (mass movements)

1. 2-4 times daily the chyme is swept rapidly along the colon by a peristaltic wave known as the "mass movements" These movements force the fecal material into the rectum.

2. In this type of movement constrictive rings occur at the distended or irritated point in the colon. 20 cm of colon distal to the constriction then contracts and haustration occurs as a unit to force the fecal material towards the rectum.

3. The force of contraction progressively grow for about 30 sec until another mass movements can occur.

The whole series of these movements usually persists for about 10 minutes to half an hour. They then disappear to return perhaps a half-day or even a full day later.