Peristalsis represents the muscular movement of various hollow organs. Among these, non-propulsive peristalsis occurs mainly in the intestine. It serves to mix the contents of the intestine.
What is nonpropulsive peristalsis?
Peristalsis represents the muscular movement of various hollow organs. Among these, non-propulsive peristalsis occurs mainly in the intestine. Peristalsis is the rhythmic muscle movement of various hollow organs such as the esophagus, stomach, intestines, or ureter. Non-propulsive peristalsis is only important for the intestine. It is not used for transport, but ensures that the intestinal contents are well mixed in the small or large intestine. Peristalsis is characterized by undulating movement of the hollow organs. In the case of the digestive tract, the movements mainly provide for the transport and mixing of the food pulp, which moves through the esophagus, stomach and intestines to the intestinal outlet. There are three forms of peristalsis. These include propulsive, non-propulsive and retrograde peristalsis. In propulsive peristalsis, the intestinal contents are transported in the aboral direction (toward the anus). Retrograde peristalsis transports the food pulp back again. This occurs, for example, during vomiting. Non-propulsive peristalsis is characterized by rhythmic segmentation and oscillatory movement that continuously mixes the food pulp or intestinal contents without transporting them further. Because of nonpropulsive peristalsis, intestinal transit takes up to 36 hours.
Function and task
After the passage of the gastric portal, the non-propulsive peristalsis of the small intestine already begins with the entry of the food pulp into the duodenum. This involves rhythmic movements of the intestine called segmentations. In the course of these movements, the digestive secretion of the pancreas is added to the food pulp and further mixed. At the same time, however, propulsive peristalsis also takes place, which transports the food pulp further. Important nutrients are absorbed via the villous movements. Thus, both propulsive and non-propulsive intestinal movements occur in the small intestine. The intestinal contents are slowly transported in an aboral direction and first enter the large intestine (colon). In the colon, mainly non-propulsive intestinal movements take place. During this process, the intestinal contents are further mixed, thickened and stored. The main movement in the colon consists of segmentations for mixing. This results in long transit times of food debris. On average, a complete passage of the intestinal contents takes about 30 to 36 hours. During segmentations, the intestinal contents often remain in the same place for a long time. Onward transport does not usually take place during these movements. Only rarely, about once to three times a day, there is a sudden propulsive mass movement of the intestinal contents toward the rectum. This mass movement is triggered by a gastrocolic reflex after a meal. By irritating the gastric receptors, a signal is transmitted to the colon via the autonomic nervous system, whereupon the propulsive mass movement occurs. This sudden mass movement is the only way to transport the intestinal contents to the anus and initiate defecation. However, the main component of intestinal movement consists of non-propulsive peristalsis, which, in addition to mixing, also contributes to the storage of intestinal contents. During segmentation, the waves of contraction of the intestinal muscles are both aboral and antiperistaltic. The prolonged retention of intestinal contents in the ascending colon (part of the large intestine) still allows sufficient water, electrolytes, and fatty acids to be absorbed. In addition, some food components are still broken down and utilized by bacteria. Control of intestinal movement is mainly provided by the autonomic enteric nervous system. The infrequent mass movement requires a signal from the direction of the stomach, which is transmitted to the colon by the autonomic nervous system. During segmentations, annular constrictions occur, which, together with the constantly increased tone of the longitudinal muscle strips (taenia), result in haustra (bulges of the intestinal wall). In the haustra, the intestinal contents are stored for a longer period of time and can thus still serve as a source of important nutrients.
Diseases and ailments
Nonpropulsive peristalsis, as mentioned earlier, prolongs the residence time of intestinal contents in certain areas of the colon. However, when the segmental contraction of the ring muscles of the colon is decreased, a disorder of nonpropulsive peristalsis is present. In this case, accelerated intestinal transit of the intestinal contents occurs. This results in thin-bodied diarrhea. Due to the shorter residence time in the intestine, the intestinal contents can no longer be sufficiently dehydrated. The causes for disturbances of non-propulsive peristalsis can be manifold. Frequently, a vegetative-functional diarrhea is present. It is caused by an increased sympathetic tone during anxiety or stress. Diarrhea can also occur in the context of irritable bowel syndrome. Here, psychological factors that influence intestinal peristalsis also frequently play a major role. In diabetic polyneuropathy, various nerves are damaged, which can also cause disturbances in non-propulsive peristalsis that can lead to both diarrhea and constipation. In this case, the finely tuned relationship between propulsive and non-propulsive peristalsis is disturbed. Depending on which nerves are affected, polyneuropathies may result in watery diarrhea or, conversely, megacolon. A megacolon is characterized by chronic constipation and an enlarged colon. Hormonal disorders also often play a major role in intestinal motility. For example, hyperthyroidism (overactive thyroid) also causes accelerated intestinal transit. In addition, many chronic bowel diseases affect the function of the ring muscles in the intestine and cause either accelerated or delayed intestinal passage.
