Question

When Va / Q is infinity?

• A. Partial pressure of \(O_2\) becomes zero
• B. No exchange of \(O_2 \;\&\; CO_2\)
• C. Partial pressure of \(CO_2\) alone becomes zero
• D. Partial pressure both \(CO_2\) and \(O_2\) remain normal

Answer 1

The Correct Option is B

The concept of Va/Q refers to the ventilation-perfusion ratio, which is a crucial factor in respiratory physiology. It represents the ratio of the amount of air reaching the alveoli (Va) to the amount of blood reaching the alveoli (perfusion, Q). In an ideal physiological condition, this ratio is balanced to ensure efficient gas exchange between oxygen (\(O_2\)) and carbon dioxide (\(CO_2\)) in the lungs.

When Va/Q approaches infinity, it indicates an imbalance between ventilation and perfusion. Specifically, an infinite Va/Q ratio means there is ventilation without corresponding perfusion. In other words, air is reaching the alveoli, but there is no blood flow to pick up oxygen or release carbon dioxide. This scenario can be described as a physiological dead space.

In this situation, there would be no exchange of \(O_2 \;\&\; CO_2\) between the alveolar air and the blood. This is because although the alveoli are being ventilated (air is present), the absence of blood flow (perfusion) means there can be no gas exchange.

Thus, the correct option is: No exchange of \(O_2 \;\&\; CO_2\).