What actually, uh, like, causes the hypoxia in lungs, making, like, the oxygen concentration lesser than 70% and, uh, um, like, the-- where the partial pressure of oxygen is lesser than, uh, 73, uh, mmHg and, uh, which leads to the, like, uh, the vasoconstriction of the, uh, hypoxial part of lung, or you can say alveoli, or-- like, tell me if, if, if this can done to a complete lung? Or not? And, like, what are the reasons and causes?

Explain the mechanism of hypoxic pulmonary vasoconstriction