The migratory motor complex is a movement pattern of the digestive tract that guides ingested food through the stomach. In this process, the muscles of the stomach and small intestine move under the control of the enteric nervous system to move food through the digestive tract. Diseases such as diabetes can cause paralysis of this movement pattern.
What is the migratory motor complex?
The migratory motor complex is a movement pattern of the digestive tract that carries ingested food through the stomach. By the migratory motor complex, medicine refers to a recurrent pattern of activity of the stomach and small intestine. The movement pattern is essential for functioning digestion when the stomach is full, as this is how food first reaches the intestines. In contrast, in a fasting state, this movement pattern is responsible for phenomena such as stomach growling. In the stomach, the migratory motor complex lasts about 90 minutes to two hours and proceeds in three phases. In the first phase, little happens. There is neither mechanical activity nor secretion formation. During the second phase, uncontrolled mild contractions of the stomach occur. In the third phase, strong gastric contractions take place, completely emptying the stomach and pushing the contents into the intestine. When the stomach is empty, there is a compaction of air in the stomach during this phase. The contractions of the fasting stomach are also known as hunger contractions. In medical terminology, this phenomenon is called borborygmus.
Function and task
In the stomach, solid food is kneaded through by gastric contractions and additionally broken down with gastric juice. The contractions of the stomach are controlled by the autonomic nervous system, which coordinates all vital vital functions. In addition to digestive movements, heartbeat and respiration are also controlled from here. The nervous system for digestion is also called the enteric nervous system and is an independent subform of the autonomic nervous system, which receives partial signals from the sympathetic and parasympathetic nervous systems. Digested food thus reaches the duodenum in portions via the stomach contractions under the control of the enteric nervous system, where digestive enzymes begin their work. In order to transport the digested food into the duodenum at all, the muscles of the stomach have to work hard. Contractions of these muscles enable the food to be transported. The stomach walls contract during this cyclically recurring pattern of movement and move toward the intestines. This movement carries food into the intestines when the stomach is full. This movement toward the intestines is tantamount to a patting out of the stomach and is essential for digestion to function. When the stomach is empty, it cannot interrupt the schematic pattern of movement, even though no food actually needs to be transported. Therefore, the contractions of the empty stomach make the stomach muscles move a mixture of air and gastric juice instead of food. This is responsible for the stomach growl. The fact that it is audible at all is due to the large volume of the resonating body. Most researchers assume that the sound of the stomach growl actually wants to call for food intake. The complex of movements of the stomach in the form of the three phases of motionlessness, slight movement and strong contraction is repeated at intervals of about one and a half to three hours. Each repetition is principally intended to empty the stomach. The migratory motor complex occurs in the small intestine in addition to the stomach. In this process, the muscles of the small intestine move in a wave-like pattern at regularly recurring intervals to move the intestinal contents into the colon. Because the pattern of movement also occurs in the small intestine via the autonomic or enteric nervous system, it is not tied to food intake here either.
Diseases and disorders
In paralysis of the gastric or small intestinal muscles, the migratory motor complex no longer occurs or occurs slowly in the affected digestive organ. For example, in chronic gastric paralysis, repetition of the motor pattern is delayed. Gastric emptying takes longer than is the average case. As a result, sufferers experience a persistent feeling of fullness, nausea or upper abdominal pain. Chronic gastric paralysis is often related to diseases such as diabetes, but viral infections and damage to the muscles are also possible causes.In diabetes, the nerves of the stomach or small intestine themselves are affected by functional impairment and are unable to receive commands from the brain or receive them only at a slower rate. Persistent disturbances in gastric emptying can expand the stomach to an unnatural volume. To be distinguished from chronic paralysis of the stomach or even the small intestine are acute paralyses of both digestive organs. In acute paralysis, no movement of any kind is possible. The migratory motor complex is therefore completely absent and the organ is permanently at rest. Acute paralysis of the digestive system can occur, for example, in the context of paraplegia. However, diseases such as Hirschsprung’s disease can also be responsible for enteric paralysis under certain circumstances. In contrast, diseases such as multiple sclerosis or ALS usually do not affect the autonomic nervous system.
