Why Your Stomach Growls When You Are Hungry?

That was one of the questions I addressed to the class while we were discussing the importance of breakfast in Health Education class.
Leony innocently responded, "The elder people I know would usually said it was the worms making noises in my stomach. They're hungry!"
"Yes! Exactly like what we see in the commercial on TV!", Vitto added as he sang along the commercial jingle and chuckled.
Rhodrick said, "It was the gas in our stomach that makes that sound."
Well, Rhodrick almost hit the point. Here's the explanation :

"When your stomach and intestines are empty, it triggers a reflexive generation of waves along your stomach and intestine muscles that trigger contractions, even though there isn’t really much of anything in your stomach that needs moved along.  These are meant to clear out all of your stomach contents, including the mucus, any remaining food, bacteria, etc.  It’s your body’s way of doing a little house cleaning, making sure no food or other matter is accumulating anywhere along your stomach or intestines.  It’s typically this that you are hearing when you’re hungry.
You might be asking yourself, “Well if my stomach is doing these contractions even when I’m full, moving food along, why don’t I hear them all the time?”  To answer that, think of the stomach as hot water bottle.  When it is full and you slosh the contents around, there is little to no noise, depending on just how full it is.  The less you have in it, the more noise the sloshing makes.  This is pretty much exactly what is going on with the stomach only the muscles lining the walls of your stomach and intestines are doing the sloshing as they push the contents of your stomach and intestines towards your derriere."

Credit : http://www.todayifoundout.com/index.php/2010/03/why-your-stomach-growls-when-you-are-hungry/