1. The passage of air from nose/mouth to lungs
Click the mouse to follow the passage of air from the nose/mouth to the lungs

2. Nose
Air enters the respiratory system through the nose and mouth. It is here that the air is warmed, filtered (by tiny hairs), and moistened. From the nose, the air passes through the throat (the pharynx).

3. Pharynx
The pharynx lies behind the nose and mouth and both cavities open into it. Both food and air pass through the pharynx, the food is then directed to the oesophagus.

4. Larynx (Voice box)
The cavity of the larynx is separated from the pharynx by a flap known as the epiglottis. This prevents food from entering the windpipe (trachea), into the lungs.

5. Trachea (Windpipe)
The trachea is approximately 10-12cm long and is kept open by a series of rings of cartilage. It contains cells which remove foreign particles from the air.

6. Bronchi
The trachea divides into two bronchi, one leading to each lung. Each bronchi then breaks up into smaller tubes known as bronchioles.

7. Bronchioles
The bronchial tubes further divide into smaller tubes called bronchioles before terminating in clusters of air sacs known as alveoli.

8. Alveoli
Alveoli look like bunches of grapes. There are millions of alveoli in each lung and it is here that gaseous exchange takes place. They have large surface areas, thin walls and are surrounded by a network of pulmonary capillaries.