Passage VI
In the human body, O2 and CO2 are exchanged between the lungs and the blood and between the blood and the tissues as indicated in Figure 1. These exchanges occur by the diffusion of each gas from a region where its partial pressure (the pressure contributed by a single gas) is higher to a region where its partial pressure is lower. The figure gives the partial pressures PO2 and PCO2 in the lung alveoli (sacs), in the tissue cells, and in the blood of a healthy resting person at sea level.
Figure 2 shows how alveolar PO2 and PCO2 vary with alveolar ventilation (volume of air per unit time available to the alveoli for gas exchange).
Figures adapted from Arthur J. Vander, James H. Sherman, and Dorothy S. Luciano, Human Physiology: The Mechanisms of Body Function. ©1985 by McGraw-Hill, Inc.
37. Based on Figure 2, if a person’s alveolar ventilation decreases from a value of 6.3 L/min, how do the person’s alveolar PO2 and alveolar PCO2, respectively, change?
Your Answer is
Correct Answer is C
Explanation
The question means that the abscissa of Figure 2 moves from 6.3 to 0, so O2 decreases, CO2 increases, choose C