What Are Intestines？

A detailed illustration of the human digestive system showing the small intestine and surrounding organs.

Are you looking for an easy way to teach your child about the human body? We’ve put together a set of free materials that parents and teachers can use right away. In this lesson, your child will dive into the fascinating world of what the intestines are. 

We’ll explore the roles of the small and large intestines in digestion. Explore science in a more engaging way with captivating 3D videos and interactive quizzes. Download our app to get started!

What You Will Learn From This Lesson

  • The small intestine is the main organ that absorbs nutrients from the food we eat.
  • The large intestine turns remaining food into poop and expels it from the body.

What Does the Small Intestine Do?

The small intestine has two primary functions: it digests food, and it absorbs nutrients from the chyme.

Structure and Function

The small intestine is a very long organ, measuring more than 20 feet. This length is about as tall as a three-story building. It has many folds that are described as being very wrinkly. These folds increase the small intestine’s surface area. This increase allows tiny projections called villi to have better contact with the chyme.

The Role of Villi in Nutrient Absorption

Villi are tiny projections that we cannot see with the naked eye. Chyme is the food after it has been turned into mush in the stomach. The intestinal villi absorb nutrients by having the chyme stick to them. There are many capillaries in each villus. Once the food is absorbed by the villi, it enters the bloodstream and flows with the nutrients throughout the body.

What Does the Large Intestine Do?

The large intestine absorbs certain substances and prepares the remaining material for removal from the body. 

  • The large intestine absorbs water and vitamin K from the remaining food.
  • A lot of good bacteria live here to break down the remaining food. This process can create a bad smell.
  • After the water and vitamin K are absorbed, the remaining food is turned into poop. This waste material is then expelled from the body.

Fun Fact

  • The small intestine is incredibly long, over 20 feet—like a three-story building.
  • If the small intestine’s folds were flattened, it would be the size of a volleyball court.
  • The large intestine contains good bacteria that help break down leftover food, which can cause a bad smell. 

Vocabulary

  • Intestines: The long, tube-like organs that are part of the digestive system. They are made up of the small intestine and the large intestine and play a key role in digestion and nutrient absorption.
  • Small Intestine: A very long organ, measuring more than 20 feet, that has two main jobs: digesting food and absorbing nutrients from the chyme.
  • Large Intestine: The organ that absorbs certain substances like water and vitamin K and prepares the remaining material for removal from the body.
  • Chyme: The food that has been turned into mush in the stomach before it passes into the small intestine.
  • Villi: Tiny projections found on the folds of the small intestine that are too small to see without magnification. The intestinal villi absorb nutrients by having the chyme stick to them.
  • Bloodstream: The flow of blood throughout the body that carries nutrients absorbed by the villi to all parts of the body.