Type of blood flow seen in the apex of the lung is
Zone 2: Intermittent blood flow only during the peaks of pulmonary aerial pressure (Ppc) because the systolic pressure is then greater than the alveolar air pressure (PALV), but the diastolic pressure is less than the alveolar air pressure.
No flow, P(ALV) > Ppc
Intermittent flow, P(ALV) < Ppc during diastole
Intermittent flow, P(ALV) < Ppc during systole
Continuous flow, P(ALV) < Ppc
Respiratory system