Your mouth, esophagus, stomach, small intestine and large intestine -- your food has a long way to go from the moment you eat it. Part of what gets it there is the natural, rhythmic movement of your stomach, which can explain the occasional growling or churning feeling you get. Special tissue types and enzymes inside your stomach make this process happen and keep digested food particles moving, which equals more energy and nutrients for you.
Two types of movements are responsible for moving food from your stomach to your intestines. The first is called propulsion -- moving your food forward, from your esophagus into your stomach and from your stomach to your small intestine. This movement requires a lot of muscle. Think about propulsion like squeezing a toothpaste tube. When you squeeze at the top, the toothpaste moves down. You may need to continue squeezing to move the toothpaste to the end of the tube. This squeezing and relaxing motions propel your food onward.
The second movement type when digesting your food is called mixing, which is needed to fully digest and absorb your food. This is similar to mixing ingredients in a mixing bowl -- if you cook a cake without mixing the ingredients first, it would not bake correctly. The same is true for mixing in your stomach and intestines. The muscles in the stomach and intestine contract at random areas to encourage mixing. As the contents become more uniform, they also become more liquid and easier to move.
While the mixing and propulsion motions move food through the body, your smooth muscle is doing the actual work. Smooth muscle lines the inner portion of the stomach. Embedded in the muscle are tiny glands called mucosa that secrete acids and digestive juices that help break down your food. If your smooth muscle becomes damaged, you cannot digest food as effectively as you once did.
Different foods pass through your stomach and intestines at different rates. Certain foods take longer to digest and may therefore remain in your stomach longer, according to the National Digestive Diseases Information Clearinghouse. Carbohydrates are easier to digest and move forward while fats stay in the stomach the longest. Proteins fall somewhere in the middle in terms of length of time in the stomach. These differences are why it is important to eat a variety of foods in your daily diet so that your stomach can constantly be providing nutrients and energy.
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