Show how the lungs are emptied and filled with air by relaxation and contraction of the diaphragm muscle!
Two balloons attached to a Y-tube simulate the lungs; the chest cavity is a plastic bell jar with open top and stout rubber sheet which acts as the diaphragm.
As the diaphragm is pulled downward, the atmospheric pressure is lowered inside the chamber causing the lungs to expand, taking in air. When the diaphragm is released the lungs deflate.
This apparatus can demonstrated the smoking effect by inserted a cigarette in the hole as figure. By pulled downward the diaphragm, we can see the smoke inhale into the lung.
