This product allows students to understand the relationship between changes in the volume of the thoracic cavity and the activity of the diaphragm This instrument consists of a transparent plastic container, an elastic rubber bottom, a rubber plug and a lung lobe model. The rubber plug is equipped with an inverted "Y"-shaped trachea made of transparent plastic, which connects two lung lobes. Before the experiment, first take off the rubber bottom and blow a little air into the lung lobes through the inverted "Y"-shaped trachea to slightly swell the lung lobes, and then insert the rubber bottom to make the transparent container form a closed space, and the lung lobes are connected to the outside air . During the experiment, pull down the drop in the middle of the rubber bottom, and you can see that the lung lobes swell obviously; loosen the bottom rubber, the lung lobes return to slightly swelled; push the rubber bottom up, and the lung lobes contract. When the rubber bottom is pulled down, the internal volume of the container increases and the pressure decreases. In order to maintain the balance of internal and external pressure, the atmosphere flows into the lung lobes; when the rubber bottom is pushed up, the internal volume of the container decreases, the pressure increases, and the atmosphere is forced. Out of the lung lobes.