Once processed and digested by the

Once processed and digested by the stomach, the milky chyme is squeezed through the pyloric sphincter into the small intestine. Once past the stomach a typical peristaltic wave will only last for a few seconds, travelling at only a few centimeters per second. Its primary purpose is to mix the chyme in the intestine rather than to move it forward in the intestine. Through this process of mixing and continued digestion and absorption of nutrients, the chyme gradually works its way through the small intestine to the large intestine.[2]
In contrast to peristalsis, segmentation involves coordinated smooth muscle contractions Migrating motor complex that result in that churning and mixing without pushing materials further down the digestive tract.
During vomiting the propulsion of food up the esophagus and out the mouth comes from contraction of the abdominal muscles; peristalsis does not reverse in the esophagus.