If Paery>Palveolus>Pvein, under normal circumstances, which zone of the lung is being described?
Zone I
Zone II
Zone III
Zone IV
Zone I ~ no blood flow (Palv> Pa>Pvein) Zone II ~ intermittent blood flow, i.e., during systole - Pa, cap>Palv>Pvein, Zone III ~ continuous blood flow (Pa>Pvein>Palv) These zones get created due to the interplay between alveolar pressure and the pressure in the pulmonary vessels. - In the recumbent posture, entire lung has zone III type of blood flow as hea would not have to pump blood against gravity to any region of the lung.
Respiratory System Pa 1