The ancient Greeks invented the word Borborygmi (pronounced BOR-boh-RIG-mee) for stomach growling, in an attempt to mimic the actual sound. When one eats, the walls of the stomach and small intestine are activated and squeeze the contents to mix and then propel food and fluids through to the large intestine. Though this activity increases in the presence of food, it also increases approximately 2 hours after the stomach and small intestine have been empty. In the latter case, the purpose is to clear out any undigestible particles, mucus, and bacteria, and keep them from accumulating at any one site.. [How thoughtful ]. The contractions may repeat every one to two hours until the next meal is ingested. Stomach growling is associated with hunger, because contractions are louder when the stomach and intestines are empty and their content doesn't muffle the sound. This is not the same as hunger pangs, which start 12 to 24 hours after the last meal and may continue for a few days before gradually subsiding. -Mark A. W. Andrews, Scientific American LINK
I Am Joe’s Stomach "I am Joe’s stomach. I am nestled high in his abdomen, on the left side, under his diaphragm, and protected by his rib-cage. When Joe eats a full meal I shape into a pouch about ten inches long; and can I stretch I can hold as much as two quarts of food! When I am empty, I am like a deflated balloon". "If Joe could only see the processing within me, he probably would not eat so much, and he would not be so fat. Whether he gulps a hamburg-with-everything, or a gourmet meal in a Holiday Inn, it is very soon mashed, churned, pulverized, and generally battered beyond recognition, (remember when your little brother “threw up’’?) But it is only by gyrations that it begins the digestive process effectively, insuring Joe’s energy and his repeated joy in eating the next meal". (Continue)