The equation for the volume of gas transferred per unit of time (Vx) includes which two variables?

• A. DL and flow rate
• B. DL and delta P
• C. Partial pressure and airflow
• D. Surface area and thickness

Answer: (B)

The equation for the volume of gas transferred per unit of time (Vx) is influenced by the diffusion characteristics between the gases, which are represented by the diffusion constant (DL) and the difference in partial pressures (delta P) of the gases involved. The term DL refers to the diffusion capacity, which indicates how easily a gas can diffuse through a membrane or tissue, while the delta P represents the driving force for diffusion, determined by the difference in partial pressures of the gas on either side of a barrier.

Thus, the equation captures the essential relationship of gas exchange: the greater the diffusion capacity and the larger the partial pressure difference, the more gas will be transferred per unit of time. This relationship is described by Fick's law of diffusion, which states that the rate of gas transfer is proportional to these two factors. Understanding this equation is crucial in the context of respiratory physiology, as it highlights the mechanisms that govern how oxygen and carbon dioxide are exchanged in the lungs and tissues.