If Paery>Palveolus>Pvein, under normal circumstances, which zone of the lung is being described?
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.
Zone I
Zone II
Zone III
Zone IV
Respiratory System Pa 1