Passage IV
The respiratory cycle for resting humans who are breathing normally has been studied by physiologists. The figure shows 4 average measures of the cycle: lung volume, air flow (the rate at which air flows into or out of the lungs), pleural pressure (the pressure in the area between the lungs and the chest wall), and alveolar pressure (the pressure in the alveoli, small sacs in the lungs where air exchange takes place). Pleural pressure and alveolar pressure are represented as values above or below atmospheric pressure (1,033 cm H2O). The next inspiration begins at the end of the pause.
18. Functional residual capacity (FRC) refers o average lung volume during the pause portion of the respiratory cycle. Based on the figure, FRC is closest to which of the following values?
Your Answer is
Correct Answer is G
Explanation
Carefully read the definition of FRC in the question stem, and look at the pause part of the top line (corresponding to the lung volume) in the figure. The value is about 2.4 L