Peristaltik

Peristaltik, or peristalsis, is a coordinated sequence of circular muscle contraction and longitudinal muscle relaxation that propagates along hollow organs to move contents. It occurs throughout the digestive tract and in some excretory and reproductive ducts.

Mechanism: In most mammals, peristalsis is generated by the enteric nervous system, with input from the myenteric (Auerbach) plexus; rhythmic slow waves set by interstitial cells of Cajal act as pacemakers. A stretch stimulus from a bolus triggers a reflex that causes the circular muscle behind the bolus to contract and the segment ahead to relax, producing forward propulsion. In the esophagus, primary peristalsis is initiated by swallowing; secondary peristalsis may be triggered by distension if a swallow fails to clear.

In the intestines, peristalsis occurs alongside mixing movements called segmentation; segmentation constricts locally to mix chyme, while peristalsis propels content distally. Peristaltic waves can also move urine along the ureters and secretions in certain ducts.

Clinical significance: Disruption of peristalsis can cause dysmotility disorders, such as esophageal aperistalsis, gastroparesis, intestinal pseudo-obstruction, or ureteral obstruction. Treatments may target smooth muscle function or neural regulation, depending on the site.

History: The peristaltic reflex and its neural control were described in the late 19th century by Bayliss and Starling, forming a basis for understanding the enteric nervous system.