The respiratory system

The human respiratory system contains the organs that allow us to get the oxygen we need and to remove the waste carbon dioxide we don't need. It contains these parts:

• lungs
• tubes leading from the lungs to the mouth and nose
• various structures in the chest that allow air to move in and out of the lungs.

Ventilation

Movements of the ribs, rib muscles and diaphragm allow air into and out of the lungs. Take care - this is called breathing or ventilation, not respiration. When we breathe in, we inhale. When we breathe out, we exhale.

Parts of the respiratory system

Air passes between the lungs and the outside of the body through thewindpipe, called the trachea. The trachea divides into two bronchi, with one bronchus for each lung.

Each bronchus divides further in the lungs into smaller tubes called bronchioles. At the end of each bronchiole, there is a group of tiny air sacs. These air sacs have bulges called alveoli to increase their surface area.