What causes Bowel Sounds?
In order for the bowel (intestines) to be heard, three conditions must be met:
- Muscular contraction of the intestinal wall
- The presence within the intestines of liquid
- The presence within the intestines of gas
While seldom of medical importance, for some a rumbling, growling stomach can be a source of embarrassment. Termed “borborygmi,” bowel sounds seem loudest to those experiencing the sounds. However, most such noises are inaudible. Many people are unaware of them or at least unconcerned.
When we are awake, our intestines rhythmically move as the walls contract and relax to mix food with secretions and move it haltingly along. The occasional “peristaltic rush” may be heard as intestinal contents are moved some distance.
It is important to separate borborygmi from other gaseous phenomena such as belching, bloating, and the passing of intestinal gas (flatus). While these may occur in the same person, they are causally unrelated.
Within the intestines, ingested fluids and solids are mixed with the daily secretion of about eight liters (two gallons) of enzyme-rich fluid, most of which is subsequently absorbed. However, fluid moving through a tube is silent – it is only when there is air in the pipes that we hear the plumbing.
In the intestine ever-present gases originate from swallowed air and the release of hydrogen, carbon dioxide, and other gases by the bacterial fermentation of undigested food in the lower gut.
Even when inaudible to the intestines’ owner, characteristic sounds may be listened to by a doctor or nurse using a stethoscope. While the noisy movement of fluid and gas occurs at all levels, the most audible sounds originate from the stomach.
- Next >>