Imagine you are in your classroom, it’s almost lunch time, and some of your students are getting antsy, and maybe a little “hangry.” Someone walks by carrying a plate of pasta with marinara sauce and mozzarella cheese, turkey meatballs, seasonal vegetables, and fresh fruit. Immediately, your sense of smell is heightened and you look around to find where this delicious savory aroma is coming from. Before you even spot the person with that plate, your salivary glands are in overdrive in anticipation of eating lunch. You have just started the first step of the digestion process.
Fast forward to the lunchroom, where you and your students have your equally delicious plates of food and are ready to enjoy a blissful meal. As you take your first bite, your digestion process is underway:
- In the mouth, saliva helps moisten your food for easier swallowing. Saliva contains enzymes that begin chemically digesting food into smaller molecules. Chewing helps to mechanically digest food.
- As you swallow, the food travels down the esophagus to the stomach, where the acidic environment inactivates the enzymes from the saliva. The stomach produces an acidic fluid mixture made of gastric juices that further digest the food.
- Once the partially-digested food passes through the stomach, it moves into the small intestine, where a multitude of digestive juices and enzymes from the liver, small intestine, and pancreas break down fat, neutralize stomach acid, and further digest carbohydrates, proteins and fats.
- Within the small intestine, several things happen at once. The food mixture breaks down to smaller nutrient molecules such as glucose or fructose. Involuntary muscles move these molecules slowly through the small intestine where most of the nutrients are absorbed into the bloodstream.
- The bloodstream carries the nutritious molecules to the liver and the rest of the body. Those small molecules provide the energy and building blocks that our cells use for growth, repair and maintenance.
- Any undigested or excess food mixture moves into the large intestine. This is where undigested carbohydrates, like fiber, are fermented, creating gas. The last step is excretion of the waste products.
Now go forth, and share your wonderful knowledge about digestion with other eaters.