After emerging from the nostrils via CGI, the presenters discuss the anatomy of the breathing system. The mechanism of breathing is described using an animation: active inhalation and passive exhalation.

First broadcast:
21 November 2008

The class should discuss respiration, the factors that affect it and how it releases energy for use in cells. Respiration and breathing in humans and other animals could be looked at and the transport of oxygen, carbon dioxide and glucose round the body discussed.