A) 1925
B) 1930
C) 1940
D) 1950
Physicians routinely give their patients pulmonary function tests in order to measure
characteristics of lung function. The most common of these tests, spirometry, measures
both the volume and the speed of air entering and exiting the lungs. In this test, a person
first breathes normally while breathing into a spirometer, a machine that measures air
volume and air speed. Then the person takes the deepest breath possible and exhales as
hard as possible for 6 seconds into the spirometer. The resulting data are plotted on a
graph of volume (y axis) versus time (x axis). Spirometry is useful not only for
assessing lung function in healthy patients but also for characterizing patients with lung
conditions such as pulmonary fibrosis, asthma, or emphysema.
A sample graph for a healthy adult male is shown below. Normal breathing occurs
between points A and B, a maximal inhalation occurs at point C, and a maximal
exhalation occurs at point D. Normal breathing resumes between points E and F.