When you think about eating, you’re probably thinking about how good your favorite food tastes and how it makes your stomach feel full. But have you ever wondered why you eat in the first place? Or have you wondered what happens to your food after you eat it? People need food to make their bodies strong and healthy. Before it can do, that food needs to take an important journey. That journey takes place in what is called the digestive system.
Your body is made up of different systems. Each of these systems has a very important job to do. Your digestive system is one of these systems. Its job is to break down the food that you’ve eaten and turn it into energy that your body can use. Before it can be turned to energy, food has to enter the body through your mouth. Your mouth is the beginning of your digestive system.
The teeth in your mouth are very important because they help prepare food to travel through the rest of your digestive system. Each tooth is strong and hard enough to chew up your food. The hard surface that you see is called the crown, and it is covered by enamel. The enamel not only makes your teeth hard, but it is also protecting the insides of your teeth. Beneath it is the dentin and the inner part of the tooth that’s called pulp. In your life, you’ll have two sets of teeth: your primary or baby teeth and your permanent teeth. Your permanent teeth start to grow and push their way out when you’re around five years old. When they push out, your baby teeth make room for them by falling out. After your baby teeth have been replaced, you’ll have 28 teeth in your mouth! When you’re older, another group of teeth called the wisdom teeth will grow in. These teeth can hurt and make your mouth a very crowded place. If that happens, the dentist may remove them.
Your teeth have a job to do. That job is to chew your food. When you chew, your teeth rip and tear the food into small pieces so that you can swallow it and not choke. Your mouth has different types of teeth, and each type helps you chew better. The types of permanent teeth are incisors, canines, bicuspids, and molars. The incisors are the teeth that do the tearing and biting: They are the four top teeth and the four bottom teeth in the front. Next to these teeth are the canines. Canines are the four longer, sharper-looking teeth, and they also help tear into food. There are two canine teeth on top and two on the bottom. On the other side of the canine teeth are the bicuspids that crush food. Sometimes, people call these premolars. The teeth that are behind the bicuspids are called molars. There are three molars: the first molar, the second molar, and the wisdom tooth. These are the teeth that grind food so that it can be swallowed. There can be three molars on each side of the mouth on the top and three on each side of the mouth on the bottom. This means that you can have 12 molars!
Your teeth also start the digestive process with help from saliva and your tongue. Saliva (you might call it spit) works with the teeth and helps make food soft and easy to swallow. It also has chemicals in it that start breaking down the food. The tongue helps to move the food around, and when you’re ready, it pushes the food down the back of the mouth to the esophagus.
The esophagus is a long tube that carries food from your mouth all the way down to your stomach. It is made of muscle and moves like a wave as it pushes down the food. Your stomach is like a sack that’s filled with very strong chemicals that are called gastric juices or gastric acid. For as many as four hours, your food moves around and mixes with the gastric juices in your stomach. This partially breaks down the food and turns it into something called chyme. The food, or chyme, leaves your stomach and enters the small intestine. The small intestine is a very, very long tube – up to 22 feet long! As your food travels through this long tube, more chemicals break it down. This includes something that the liver stores in the gallbladder called bile, as well as chemicals from the pancreas. As the food mixes with the different chemicals, it breaks down into molecules, pieces that are tiny enough for the body to use. The walls of the small intestine absorb these molecules and send them into the bloodstream so that they can be put to work and help give your body what it needs. The remaining food exits the small intestine and enters the large intestine. The large intestine removes water from the remains of the food. This is the final stop before the food that you ate exits your body from the anus as waste, or poop.
Who knew that food went through so much! Your digestive system is very important to all of the things that you love to do. It turns your favorite foods into energy so that you can jump, run, play, and laugh! Your teeth are an important part of your digestive system. They help you chew up your food really well, so always brush them and help keep them nice and strong. They are the starting point for the very important journey that your food has to take.
The links below will help you learn more about your teeth and your digestive system. Take a look!
- Movie: Digestive System
- Digestive System Animation Grade 3 to 12 (Video)
- Body Zone – The Digestive System
- Lesson Plan for Grade 4: Digestion Process (PDF)
- Have you Ever Wondered Why We Need Our Teeth to Chew Our Food?
- Teeth and Gums: Different Kinds of Teeth
- Why Do We Need Teeth?
- Teeth – What Are They?
- Your Organs – It’s All a Part of the System