<prompt> A subject inspires a mixture of gases containing carbon monoxide and holds his breath for 10minutes. During those 10seconds, alveolar Pco is 0.5mmHg and the CO uptake is 25mlmin. Which of the following is the diffusing capacity of the lung for CO?5 mlminmmHg15 mlminmmHg50 mlminmmHg150 mlminmmHg  <response>: DLCO amount of CO entering the blood VCO divided by paial pressure of CO in the alveoli PACO minus the paial pressure of CO in the blood entering the pulmonary capillaries. Except in habitual cigarette smokers, this latter term is close to zero DLCO VCO PACO 250.5 50 mlminmmHg 