Movement in the Digestive Tract
The rhythmic contraction of smooth muscle in the wall of the gut helps to propel, mix, and churn the food. The contraction of the smooth muscle is initi-ated by “pacesetter” cells. The pacesetters are smooth muscle cells in the proximal part of the gut that spon-taneously generate impulses and action potential. These impulses travel down the gut via the smooth muscle, as well as the network of autonomic nerves in the wall, creating waves of muscular contraction. The wave of muscular contraction that travels along the length of the digestive tract is known as peristalsis. In most areas of the small intestine, other than peristal-sis, the circular muscles contract to churn and mix the food material, not necessarily to propel it forward. This movement is known as segmentation.