So there you are, sitting at lunch, enjoying some grilled chicken pizza and a few orange wedges. When you're finished, you take a last drink of milk, wipe your mouth, and head to your next class. In a few minutes you're thinking about the capital of Oregon or your science fair project. You've completely forgotten about that pizza lunch you just ate. But it's still in your stomach - sort of like a science experiment that happens all the time!

Your digestive (say: dye-jes-tiv) system started working even before you took the first bite of your pizza. And the digestive system will be busy at work on your chewed-up lunch for the next few hours - or sometimes days - depending upon what you've eaten. This process, called digestion, allows your body to get the nutrients and energy it needs from the food you eat. So let's find out what's happening to that pizza, orange, and milk.

The Mouth Starts Everything Moving
Even before you eat, when you smell a tasty food, see it, or think about it, digestion begins. Saliva (say: suh-lye-vuh), or spit, begins to form in your mouth. When you do eat, the saliva breaks down the chemicals in the food a bit, which helps make the food mushy and easy to swallow. Your tongue helps out, pushing the food around while you chew with your teeth. When you're ready to swallow, the tongue pushes a tiny bit of mushed-up food called a bolus (say: bow-lus) toward the back of your throat and into the opening of your esophagus, the second part of the digestive tract.

The esophagus (say: ih-sah-fuh-gus) is like a stretchy pipe that's about 10 inches (25 centimeters) long. It moves food from the back of your throat to your stomach. But also at the back of your throat is your windpipe, which allows air to come in and out of your body. When you swallow a small ball of mushed-up food or liquids, a special flap called the epiglottis (say: eh-pih-glah-tiss) flops down over the opening of your windpipe to make sure the food enters the esophagus and not the windpipe.

If you've ever drunk something too fast, started to cough, and heard someone say that your drink "went down the wrong way," the person meant that it went down your windpipe by mistake. This happens when the epiglottis doesn't have enough time to flop down, and you cough involuntarily (without thinking about it) to clear your windpipe.

Once food has entered the esophagus, it doesn't just drop right into your stomach. Instead, muscles in the walls of the esophagus move in a wavy way to slowly squeeze the food through the esophagus. This takes about 2 or 3 seconds.

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