What is the pathway taken by air in the respiratory system? Illustrate with a labeled diagram. (AS5)

A. The pathway taken by air in the respiratory system:

Nostrils —› Nasal Cavity —› Pharynx —› Larynx —› Trachea —› Bronchus—› Bronchioles —› Alveoli —› Blood

1. Air enters the body through the nostrils.

2. Air is filtered by a hair in the nasal cavities.

3. Nasal cavities lead into the trachea is also called the wind pipe.

4. Trachea after entering into lungs divides into 2 bronchi one leading to each lung.

5. The bronchi further divide into smaller and smaller branches called bronchioles.

6. Bronchioles finally terminate in clusters of air sacs called alveoli in lungs which are very small and numerous.

7. Gaseous exchange takes place here as blood capillaries take up oxygen and expel carbon dioxide here.

8. Blood carries oxygen to each and every cell of the body. The whole passage from nostrils to alveoli is moist and warm.