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Digestive System

Have you ever wondered what happens to the food you eat? Where does it go, and why does your body need food, anyway? The food you eat travels through your digestive system. This organ system starts at your mouth and ends at your anus. The digestive system extracts energy and nutrients from food to fuel your body.

Illustration of the digestive system in the human body.

The Digestive Organs

The digestive system contains 9 major organs. The hollow organs include the mouth, esophagus, stomach, small intestine, large intestine, and anus. The solid organs include the liver, gallbladder, and pancreas. Take a look at the diagram below to see where everything is.

Imagine that you’ve just eaten a yummy lunch—maybe a peanut butter and jelly sandwich, or a piece of pizza. Let’s follow that lunch at it travels through the digestive system. On our journey, we’ll discover the role of each of these organs. Bon voyage!

A diagram of the digestive system

A diagram of the digestive system

Chewing and Swallowing

First stop: the mouth, of course! Your mouth begins the process of breaking down your lunch so you can swallow it. Additionally, you teeth grind up your lunch and your salivary glands excrete saliva. Saliva contains chemicals that break down the food even more.

Your tongue helps to create a moist ball of chewed-up food called a bolus. You swallow the bolus, and it enters the esophagus. The esophagus is a long, stretchy tube about 10 inches long that connects your mouth to your stomach.

A flap called the epiglottis covers the opening of your windpipe when you swallow. That way, food doesn’t accidentally enter your lungs. Have you ever had food “go down the wrong pipe?” That means your epiglottis didn’t close fast enough!

The muscles in the walls of your esophagus squeeze your lunch into your stomach. This squeezing is called peristalsis. It takes about 1-2 seconds for your lunch to move from your esophagus into your stomach.

Digestion in the Stomach

Your lunch has finally made it to your stomach, a J-shaped sack in your upper abdomen. When empty, your stomach is about the size of a tennis ball. But, when it’s full, it can be as large as a football! Your stomach stores your lunch, digests it some more, and then sends it on its way to the small intestine.

Your stomach wall secretes gastric juices. These aren’t the kind you drink! Instead, these juices help to break down food and kill bacteria. Your stomach muscles churn the food to break it down some more. Now, your lunch has transformed into a soupy mixture called chyme.

Chyme bubbling in the stomach

Chyme bubbling in the stomach

Digestion in the Small Intestine

Next stop, the small intestine. Funny enough, your small intestine isn’t so small. An adult’s small intestine is 22 feet long! However, it’s all bundled up, so it doesn’t take up much space. The small intestine digests your lunch—now chyme—even further. This helps you absorb nutrients into your bloodstream.

The small intestine does all this with a little help from the solid organs of the digestive system. These organs secrete their juices into the small intestine to help with digestion.

The pancreas secretes juices that digest fats and protein.

The liver secretes bile, which helps absorb fats.

The gallbladder stores extra bile.

The food stays in the small intestine for about four hours. During this time, it becomes a thin, watery mixture. Just like in the esophagus, the muscles in the small intestinal walls squeeze the food to keep it moving. Do you remember what we call this process? Peristalsis!

The watery remains of your lunch move through the small intestine. Here, finger-like bumps help you absorb nutrients into your blood. These nutrients can include fats, proteins, carbohydrates, and minerals. They give your body the fuel it needs to function. It’s important to eat healthy foods so your body has all the nutrients it needs.

Illustration of a the digestive system with all the organs named.

Check out all the organs that are involved with digestion. Each organ has an important job to perform.

Digestion in the Large Intestine and Anus

It’s time for your lunch—or what’s left of it, at least—to enter the large intestine. At 5 feet long, the large intestine is much shorter than the small intestine. It’s called the large intestine because it’s much thicker around. The large intestine absorbs water and the last bits of nutrients from you lunch.

Can you guess what’s leftover after? It’s brown, stinky, and gross…

Poop, that’s right! It forms after your digestive system has taken everything your body needs from the food. The poop travels to your rectum at the end of your small intestine. The rectum stores your poop. When you’re ready to go to the bathroom, poop exits through the anus.

It doesn’t look much like the sandwich you had for lunch, does it?

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Written by: Daryth Gayles