Digestive System

In order for your body to grow, you must consider the foods that you eat that give you energy and help your body to run, think, work and even play.

There are six different kinds of nutrients that food contains and these different nutrients; vitamins, minerals, water, protein, fats, and carbohydrates, help your body to be healthy.


Nutrients that are inside foods are needed for anything living to survive. Some foods contain all of the six nutrients in one, while other foods contain just a few of the nutrients.

Some of the nutrients such as carbohydrates, fats, and even some proteins are too big to be absorbed by the body and they must pass through the body through the blood.

In order for this to happen though, the body must break these nutrients down into smaller molecules and this is called digestion.

Where Does Digestion Start?

Digestion starts with the mouth and with the teeth, the saliva, and the tongue.

The teeth help tear the foods, breaking them down, the saliva or the salivary glands, help moisten the food so that it is easier to swallow, and then the tongue helps to push the food and mix it with the saliva.

With all of this happening, a ball of food, or the bolus, is formed and the muscles in your mouth and throat help to push the food down.

A flap closes off the trachea when you swallow so that the food does not enter the windpipe.
This whole process is called ingestion, which means the process of taking food into the body.

To the Esophagus

The food, which is now basically liquid, then moves into the esophagus which is a muscular tube that is located between the mouth and the stomach and this tube leads into the stomach.

It takes around six seconds to move down the esophagus.

The esophagus is coated with thick mucus that helps the food to move down easily.
When the muscles in the esophagus contract, this is called peristalsis.

Food digestion does not happen because of gravity alone, but due to the contractions (peristalsis), that happen behind the food.

The Stomach

The stomach is also a muscle and these muscles are used to mix the food and in the stomach are acids and enzymes which help to mix the food and continue helping with digestion of the nutrients.

The stomach is made up of three different layers of muscles and the churning of the stomach along with the chemicals such as pepsin and hydrochloric acid, allows the food to turn into smaller proteins.

The stomach is protected from these acids because of the mucus that coats the walls of the stomach.

Small Intestine

n around 3-7 hours, the stomach continues to move through the digestive system, and it enters the small intestine.

Even though it seems that the stomach would have the biggest job of digesting, the small intestine plays the biggest role in this.

Here in the small intestine, many of the carbohydrates, fats and proteins are completely digested here.

The liver and the pancreas help to give juices to the small intestine that will help with digestion. It takes 3-5 hours for the food in the small intestine to be digested.


Carbohydrates, fats, proteins, vitamins, and minerals go through the walls of the intestine and into the blood, this is called absorption.

Absorption is the process of moving nutrients from the intestines to the blood. The circulatory system helps to transport these nutrients to the body.


When the food travels from the small intestine, it is now full of food and water that is not digestible.
The indigestible food passes through by the appendix, which is shaped like a finger. It is unknown what the appendix is really used for.

Large Intestine

The indigestible food goes into the large intestine, which is wider than the small intestine and horseshoe-shaped.

Within 18-24 hours, the water is getting absorbed into the blood and traveling through the body. Helpful bacteria such as vitamin K and vitamin B is found in the large intestine and help the body.

The food that is not digested is formed into a solid material. This solid material also contains dead bacteria, fats, and even mucus. This is called waste.


This moves into the rectum for storage and then it leaves the body through the anus, at the bottom of the rectum.
This is called elimination. Elimination is the process of moving wastes from the body.

Facts About the Digestive System:

An adult small intestine is around 23 feet long.

The liver produces bile, a soft solution that breaks down fat into smaller fat. Bile is not an enzyme.

The liver is located to the right of the stomach.

When the bile is made, it is stored in the gall bladder until the small intestine needs it.

The pancreas is located between the stomach and the small intestine.

The pancreas makes pancreatic juice and sodium bicarbonate.

Carbohydrates are broken down into simple sugars.

Proteins are broken down into amino acids

Fat is broken down into fatty acids and glycerol.

The walls of the small intestine are covered with villi, small fingerlike structures. These villi help to absorb nutrients.

The adult large intestine is 1.5 meters or 5 feet long.

Fun fact: If the whole digestive tract was stretched out, it would be 9 meters long, around 30 feet, and it would be the length of a school bus!

Vitamins help to promote health and growth.

Minerals help build body structures and keep them healthy.

Fats help build cells and store fat.

Water is the most important nutrient of the body and the body has to have water to live.

Proteins help to build and repair body tissue, including muscles.

Carbohydrates are the biggest sources of energy for the body.

What Did You Learn?

What is the process of taking food into the body? Ingestion is the process of taking food into the body.

Where does digestion start? Digestion starts with the mouth, teeth, saliva, and tongue. This is the first part of breaking down the food indigestion.

What is the process of moving nutrients from the intestine into the blood called? Moving nutrients from the intestine into the blood takes place with absorption.

Which is longer, the small intestine or the large intestine? Even though the large intestine has the name large, it is actually shorter but fatter than the small intestine.

When waste is removed from the body, it is called what? Removing waste from the body is called elimination. This is when solid food completely leaves the body.

How many nutrients do foods contain? The foods contain six nutrients; carbohydrates, fats, vitamins, minerals, water, and proteins.