Waterfall effect is seen in which pa of lung?

Water fall effect describes blood flow in the middle poion of lung. Middle poion of lung: Blood flows in pulses. Initially - No flow due to of obstruction at the collapsed venous end of the capillary Pressure from the aerial side builds up until it exceeds alveolar pressure and flow resumes-Dissipates the capillary pressure- Returns to the sta of the cycle. The blood flow in this region is determined by the pulmonary aery-alveolar pressure difference. Blood "falls" into the pulmonary veins, which are compliant and take whatever amount of blood can flow into them. This has been called the waterfall effect.