Simulation of oxygen diffusion through the respiratory membrane

The final stage of transferring oxygen to blood involves diffusion of gases through a very thin semi permeable membrane called respiratory (alveolar-capillary) membrane. The rate of diffusion of oxygen across this membrane is directly proportional to the membrane area (70 m2), oxygen diffusivity through the membrane (4×10-12 m2 s-1), partial pressure gradient of oxygen across the membrane (104 mmHg in the air of alveolus side and 40 mmHg in the blood of capillary side), and inversely proportional to the membrane thickness (1 µm). In this study, the model of respiratory system (alveolus, membrane and capillary) which is obtained by making a mass balance, as a function of time, for oxygen was simulated using FEMLAB software. The concentration and flux distribution as well as variation of concentration with length in respiratory system after 0.01, 0.1, 1 and 2 seconds were illustrated as software outputs. The results showed that as the process proceeds, the difference in concentration between the alveolus and capillary chambers decreases. After two seconds oxygen concentration at alveolus and capillary became identical. This means that, considering respiration rate of 20 breaths per minute for an adult person at rest, diffusion through respiratory membrane is a controlling stage in respiration process.

کلیدواژه ها:

Simulation ، FEMLAB Software ، CFD ، Gas Separation ، Respiratory Membrane