What does V/Q mismatch refer to in respiratory physiology?

V/Q mismatch refers to an imbalance between ventilation (the air that reaches the alveoli) and perfusion (the blood that reaches the alveoli). In respiratory physiology, an ideal state is when ventilation and perfusion are matched, allowing for optimal gas exchange. When this balance is disrupted, it can lead to conditions where either ventilation is inadequate for the amount of blood flow or the blood flow is inadequate for the volume of air available for gas exchange.

B correctly captures the essence of V/Q mismatch by highlighting the imbalance of blood flow and ventilation. This imbalance can occur in various respiratory conditions, influencing oxygenation and carbon dioxide removal from the blood. For example, a lung area may be well-ventilated but poorly perfused, or vice versa, resulting in reduced efficiency of gas exchange. Understanding V/Q mismatch is critical for diagnosing and managing various pulmonary diseases.