The Respiratory System

What is the respiratory system?

The respiratory system is the set of organs and other body parts that supplies the body with oxygen and gets rid of carbon dioxide. Look at the diagram below which shows the parts of the human body which make up the respiratory system.

How does the respiratory system work?

When we inhale (breathe in), air enters the body through the nose or mouth and into the pharynx (throat). It then passes through the larynx and into the trachea or wind pipe. The trachea splits into two tubes called bronchi. Each bronchus enters a lung where it splits into smaller and smaller tubes. The air we breathe passes through these tubes. The smallest tubes are called bronchioles. These tiny tubes lead to small air sacs called alveoli which fill up when we inhale. There are millions of alveoli in in your lungs. A gas called oxygen from the air we breathe in then passes from these alveoli and into small blood vessels in the lungs. At the same time another gas called carbon dioxide passes from the tiny blood vessels and into the alveoli. Then we breathe the air back out (exhale) to get rid of the carbon dioxide. A muscle called the diaphragm helps us breathe. When it moves down it helps us breathe in and when it moves up it helps us breathe out.

What happens next?

Every part of our body needs oxygen to survive. After the tiny blood vessels pick up oxygen in the lungs, this blood flows to the heart. The heart then pumps the oxygen rich (oxygenated) blood all around the body through blood vessels. As the oxygen is used up, a waste gas called carbon dioxide is produced and is passed into the blood. The oxygen poor (deoxygenated) blood then flows back to the heart which pumps it to the lungs to get rid of the carbon dioxide and pick up more oxygen.

Fun fact: The larynx helps us speak. We can use the air we exhale to vibrate vocal cords in our larynx. As the vocal cords vibrate, they make sounds. We can move the larynx up or down to make higher or lower pitched sounds. Continue the lessons to see two videos about the respiratory system.