Chapter 24, Problem S5.4BYB

Summary Introduction

To determine:

The factors, which influence the diffusion of gas across the membrane.

Introduction:

During the process of respiration, the gaseous exchange takes place between the bloodstream and the body cells by the process of diffusion.

Explanation of Solution

In the body, the process of respiration takes place, in which the carbon dioxide and oxygen gas exchange between the body cells and bloodstreams. Diffusion of gases across the respiratory membrane depends on the various factors such as membrane thickness, the surface area of the membrane, the diffusion coefficient of gas and difference in the partial pressures of gas between the two sides of the membrane.

As in case of fibrosis in the lungs , the thickness of respiration membrane increases, which ultimately make it difficult for the gas to diffuse out because the rate of diffusion through the membrane is inversely proportional to the thickness of the membrane. As in case of emphysema , the total surface area gets decrease due to loss of alveolar walls. The decrease in surface area will lead to decrease in gaseous exchange.

For the gaseous exchange through the membrane, the diffusion coefficient depends upon the gas solubility of the membrane and inversely with the square root of gas molecule weight. The difference in pressure across the membrane is the difference between the partial pressure of the gas in the alveoli and partial pressure of the gas in the blood. Hence, the difference between the two pressures is mean of diffusion of gas to move across the membrane.

Conclusion

Hence, the rate of diffusion depends upon these above factors. These factors mainly influence the diffusion across the membrane.