It happens when your stomach is trying to digest food but it can't because there is nothing in there. So it has to produce more mucus to keep it from digesting itself. Once the output gets past a certain point it starts to make noises so that you know it needs sustinence or it will run out of its stockpile of resources soon. that is trying to make it summarized
Stomach growling, which originates in the stomach and the small intestine, can be explained by a closer look at how the digestive system functions.The digestive system is, in essence, a long tube that starts at the mouth and ends at the anus. This tube connects with the various organs and passages that play important roles in digestion. One of the most important things to know about the digestive system is the manner in which it propels food. Waves of muscle contractions move and push the contents continually downward in a process called peristalsis. In addition to moving your meal along its digestive path, these contractions also help churn food, liquid and different digestive juices together, rendering them into a gooey mix known as chyme. The rest on comments.