Use this small model to introduce and reinforce the concept of pressure as a driving force in respiration. The lungs (3" balloons) are housed in a hard plastic bell jar (3-1/4 x 2-3/4") representing the thoracic cavity. Unlike other models, the diaphragm is molded to fit securely on the bell jar without further attachments.
It is also made of thick, durable vinyl that resists thinning and tearing over time. Pull down on the diaphragm to decrease the preSsure in the thoracic cavity and increase its volume. These changes cause higher-pressure atmospheric air to fill the lungs.