Question

If $P_{atm} = 0\, mm \,Hg$ and $P_{a|v} = - 2\, mm \,Hg$, then

• A. it is the end of the normal inspiration and there is no airflow
• B. it is the end of the normal expiration and there is no airflow
• C. transpulmonary pressure $(P_{tp})$ is $- 2\, mm\, Hg$
• D. air is flowing into the lungs

Answer 1

Answer: (D)

If alveolar pressure $(P_{a|v})$ is negative with respect to atmospheric pressure $(P_{atm})$, then driving force for airflow is inward i.e., from the atmosphere into the lungs.