Why does our stomach rumble sometimes?

Sometimes it is very embarrassing: you are in a quiet place and suddenly your stomach makes strange loud rumbling noises. The worse is, there is nothing you can do about it. Imagine the anguish of someone in hiding, given away by his stomach! That never happens in adventure films! We are led to believe that cinema heroes have stationary intestines which are always full; unless, of course, they know how to control them! Actually it is the movements of the intestine which are responsible for the noise.

The muscles in the intestinal walls contract and relax rhythmically to propel the food pulp from the stomach. The muscles are arranged in two ways; some in a ring and some lengthwise. The contractions of the ring-shaped muscles form constrictions, which push the food forward. The contractions of the lengthwise muscles help sections of the intestine to ripple and bend. These movements are controlled by the autonomic nervous system, which ensures the automatic operation of all organs.
In addition, the intestines have a certain control over their movements independent of the autonomic nervous system: for example, when a small section of intestine is detached and placed in a nutritive, oxygenated solution, it continues to ripple and contact. There is, therefore, a continuous motion in the abdomen.

The noises are generally inaudible, but they may become lower when the food pulp is in short supply or when it is in a fairly liquid state. There is no doubt that these ‘rumblings’ are most often heard when we are hungry. Since the intestines do not obey instructions from us, there is nothing we can do about them.