An area of the lung has no blood flow but is normally ventilated. Which of the following statements are true about this area?
I .The alveolar gas is like air (PO₂ = 150; PCO₂ = 0) .
II.The area represents alveolar dead space.
III.The $\dot { V }$ / $\dot { Q }$ is elevated.

Question

An area of the lung has no blood flow but is normally ventilated. Which of the following statements are true about this area?
I .The alveolar gas is like air (PO₂ = 150; PCO₂ = 0) .
II.The area represents alveolar dead space.
III.The

\dot { V }

/

\dot { Q }

is elevated.

Quizplus · Accepted Answer

In an area of the lung with no blood flow but normal ventilation, the alveolar gas composition will resemble that of inhaled air because there is no exchange of gases with the blood, making statement I true. This scenario is an example of alveolar dead space, where air reaches the alveoli but no gas exchange occurs due to the absence of blood flow, making statement II true. The ventilation-perfusion ratio ($\dot { V }$/$\dot { Q }$) is essentially infinite because ventilation is normal while perfusion is zero, making statement III true.

An Area of the Lung Has No Blood Flow but Is