Question

write the exception of PA and PV​

Answer 1

Answer:

The zones of the lung divide the lung into four vertical regions, based upon the relationship between the pressure in the alveoli (PA), in the arteries (Pa), in the veins (Pv) and the pulmonary interstitial pressure (Pi) :

Zone 1: PA > Pa > Pv

Zone 2: Pa > PA > Pv

Zone 3: Pa > Pv > PA

Zone 4: Pa > Pi > Pv > PA

This concept is generally attributed to an article by West et al. in 1964,[1] but was actually proposed two years earlier by Permutt et al.[2] In this article, Permutt suggests "The pressure in the pulmonary arteries and veins is less at the top than at the bottom of the lung. It is quite likely that there is a portion of the lung toward the top in an upright subject in which the pressure in the pulmonary arteries is less than alveolar pressure."