The invention relates to a device for representing the lung, the volume of the lung, and the respiration characteristics of the lung, comprising a Y-shaped tube containing a main tube (10) which branches into a first branch (20) and a second branch (30), whereby one branch (20,30) is provided with an obstruction (50). A device for collecting and/or determining an amount of gas (100) introduced therein is disposed at the end of the two branches (20,30). The invention also relates to the use of the above-mentioned device which can act as a model in patients suffering from obstructive respiratory tract diseases. The inventive device provides an easy-to-use model for the representation of the functions of the lung, particularly in the case of restrictions such as COPD.