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Structure of the Digestive System

Structure of the Digestive System

Structure of the Digestive System

We will look at the organs that make up the digestive system, and their functions.

What do you think the function of the digestive system is?

The digestive system is __________ where organs work together to digest and absorb food.


The digestive system helps to break down food into small, soluble molecules.

All of the structures in the picture make up the alimentary canal. Digestion starts in the mouth.


Your teeth kicks off digestion by chewing the food.

Glands secrete saliva and the cheeks and tongue move food around for effective chewing. When the food has been broken up enough, we swallow it.


When we swallow food, it moves from the mouth to the oesophagus.

Muscles in the oesophagus contract in a rhythmic way that moves food down into the stomach. You'll learn more about this later.


Which structure do you think makes sure that food goes down the oesophagus and not ** the trachea? We don't want food in the lungs!


The oesophagus leads to the stomach.

The stomach contains hydrochloric acid, which destroys germs that we might eat. Enzymes are also released in the stomach. The walls of the stomach move to mix the food even more before it moves to the next area.


What lines the stomach walls?


Why do you think the mucus lining is there?

A) To make sure the acid doesn't destroy the walls of the stomach. B) To mix with the food so it will run smoother through the rest of the system. C) To make sure the food doesn't dry out in the stomach.

Why do you think you have saliva in your mouth? Why it would need to mix with the food?

Where does digestion start?


From the stomach, food moves into the small intestine, namely the duodenum. There are two ducts that join up and open into the duodenum. One duct is from the gall bladder. Where is the other duct coming from?


The gall bladder and the pancreas...

secrete substances that help with digestion. You will learn more about this later.


After the duodenum, food travels along the ileum, which is the small intestine that links the duodenum and large intestine.

It's called the small intestine because it is a narrower tube than the large intestine. But it is actually very long and not small at all. This is where the most nutrient absorption takes place and the walls of the small intestine are adapted for maximum absorption.


Finally, food moves into the large intestine and out through the anus.

The colon and rectum make up the large intestine and this is where the most water absorption happens. By absorbing water from the food passing through, the food solidifies a little, and we can pass it out of the body easily through the anus.

Ducts from which two organs join up before entering the duodenum?

You can select multiple answers

Name the small intestine that links the duodenum and large intestine.

Where does the most nutrient absorption take place?

Which two structures make up the large intestine?

You can select multiple answers