Question

Through mechanisms of ventilation-perfusion coupling, an increase in air flow to the lungs will drive a decrease in blood flow to the lungs.

True

False

Answer 1

Ventilation means the amount of oxygen reaching the lungs. Perfusion is the amount of blood received by the lungs.

The ratio of the pulmonary ventilation to the pulmonary blood flow for the whole lung at rest is about 0.8.

V/ Q = 4.2 L/min
   ------------- = 0.8
   5.5 L/min

If the ventilation to an alveoli is reduced relative to its perfusion,the PO2 in the alveoli falls because less O2 is delivered to it but PCO2 increases because less CO2 is expired.
Ventilation perfusion coupling includes the mechanisms undertaken by the body to maintain the V/Q ratio. The coupling is done by dilation and contraction of arterioles and bronchioles.
No, when the air flow to the lungs increases, the blood flow to the lungs does not decrease. Insstaed it increses to compensate the increase in blood flow..
This is achieved by causing vasodilation of the arterioles which inc​reases the perfusion or blood flow to the lungs. Ventilation Perfusion coupling facilitates efficient gas exchange.