<prompt> During standing, pulsatile blood flow is found in which of the zones in healthy lung?Zone 1Zone 2Zone 3Zone 4  <response>: Ans. B. Zone 2a. Intermittent or pulsatile flow is found at Zone 2 which is found in apex of healthy lungs.b. Zone 3 is base, and has continuous flow arterial pressure venous pressure alveolar pressurec. Zone 1 doesnt occur in normal physiological conditions. If found, it would be in apex. Here alveolar pressure arterial pressure venous pressure; so there is no blood flow. Zone 1 represents alveolar dead space. Such regions can form when pulmonary arterial pressure falls to very low eg. In hemorrhage; Or when alveolar pressure is very high eg. Positive pressure ventilation.d. Zone 2: arterial pressure alveolar pressure venous pressure: Waterfall effect pulsatile flow 