The Adventure of Your Food: Science Behind Digestion

Audience: Elementary and Middle School Students

A delicious meal you might share with your friends and family. But have you ever wondered what happens to it after you eat it? By Getty Images from Unsplash. 

What’s your favorite food? Is it pizza? Burgers? Or my personal favorite, ice cream? Well, have you ever wondered how the delicious food you eat becomes the waste we get rid of when we go to the bathroom? When you take a bite of your favorite food, it doesn’t just magically disappear. Your body works like a superhero team to break down that food into tiny pieces. With the help and teamwork of your organs, your body is able to break down your delicious lunch into helpful nutrients it can use! This process is called digestion.

First up, your food enters your mouth. In your mouth, you have up to 32 teeth that break up your food into smaller pieces. There are four different types of teeth: incisors, canines, premolars, and molars. These are used for different purposes, such as ripping food or crushing it or grinding it. You also have a lot of saliva (you may know this as spit!) in your mouth, which is actually filled with chemicals called enzymes that help make the food mushy and easy to swallow. At the same time, your tongue helps you taste and move your food around. When this process is finished in your mouth, the food is now a mushy little ball called a bolus. Time to go to the next destination! 

• ! Look in the mirror and open your mouth. Can you count your teeth? How many do you have? Can you tell the difference between how they look?

The bolus then moves down the 25-cm long stretchy esophagus, which is like a tube that connects your mouth to your stomach. This is located in the front of your neck. Can you feel it move when you swallow? The movement you feel is the food moving down your neck in a motion called peristalsis. Try saying that three times in a row!

Did you know? The trachea, or the windpipe where the air you breathe enters, is also located in your neck, behind the esophagus! That’s why when you eat or drink something too fast and have to cough it up, people say it “went down the wrong tube”. Luckily, you have the epiglottis, a little flap that makes sure your food goes down the esophagus and doesn’t enter your breathing tube. 

The next stop is a stretchy muscular pouch you know as the stomach. The stomach shares space in your tummy with other important organs. Think of your stomach as a mixer—your stomach takes the mushy food ball from your esophagus and mixes it with enzymes to create an acid-y soupy mixture called chyme.

• ! The acid in your stomach is strong enough to dissolve a nail! To protect your stomach from this, it has a protective layer that makes sure your stomach doesn’t dissolve. This does not mean you should eat a nail. Ever.

The chyme then enters the intestines. There are two parts to the intestine:

The small intestine is first, and it’s actually not that small—it can be more than 20 feet long. (That’s like 5 of you standing on top of each other!) The small intestine has three parts: the duodenum (first part), jejunum (middle part), and ileum (last part). It breaks down your food further using enzymes and picks out the helpful nutrients so your body can use it to function and grow. It also has the important job of absorbing water!

The large intestine is actually shorter than the small intestine, but it is thicker by about 1 cm. It picks up all the nutrients and absorbs all the water that the small intestine missed (hey, the small intestine makes mistakes too! Good thing your body double-checks). The large intestine also leads the remaining indigestible matter (things that you cannot digest) to the last stop of the digestive system: the rectum. When you go to the bathroom, your body gets rid of all of these indigestible things as waste.

Woo, now we’re finally done digesting! Unless… you eat something else… Then we go through the whole cycle all over again. Regardless, now you see the complex and detailed journey that the food you eat goes through. Keeping your digestive system healthy is key to feeling good and having lots of energy for all the things you love to do. To do this, make sure to eat lots of fruits, veggies, and whole grains that have important nutrients. Drink plenty of water, chew your food well, and don’t forget to move your body with fun activities and get plenty of sleep so your digestive system stays strong. So the next time you take a bite from your favorite meal, remember the remarkable system your body goes through to digest it, and keep your digestive system happy!

Bibliography

“Anatomy, Abdomen and Pelvis: Abdomen - StatPearls.” NCBI, https://www.ncbi.nlm.nih.gov/books/NBK553104/. Accessed 8 March 2025.

“The human digestive system.” National Geographic Kids, https://www.natgeokids.com/uk/discover/science/general-science/your-digestive-system/. Accessed 8 March 2025.

“Small Intestine: Function, Parts, Length & Location.” Cleveland Clinic, https://my.clevelandclinic.org/health/body/22135-small-intestine. Accessed 8 March 2025.

“Teeth: Anatomy, Types, Function & Care.” Cleveland Clinic,

https://my.clevelandclinic.org/health/body/24655-teeth. Accessed 8 March 2025.

“Your Digestive System (for Kids) | Nemours KidsHealth.” Kids Health, https://kidshealth.org/en/kids/digestive-system.html. Accessed 8 March 2025.