Lungs And Gas Exchange: Understanding Diffusion Factors

Lungs And Gas Exchange: Understanding Diffusion Factors

Describe factors determine oxygen uptake in lung.
Answer:

Factors determining oxygen uptake in lungs:

1. Pressure gradient:

• Uptake of oxygen by the blood in the lungs in mainly favoured by oxygen pressure gradient.

• Thus, because of this pressure gradient. O₂ rapidly diffuses from alveoli through the thin pulmonary and capillary endothelium into the plasma.

2. Thickness of respiratory membrane:

• Diffusion is inversely proportional to the thickness of respiratory membrane.
• In pulmonary fibrosis or edema, the thickness of respiratory membrane increases due to collection of fluid in the membrane.
• This decreases the diffusion.

3. Surface area:

• Diffusion of gases is directly proportional to the surface area of the respiratory membrane.
• During block in pulmonary capillary, the surface area of the membrane decreases.
• During exercise, surface area increases and thus diffusion of O2 also increases.

4. Solubility of gas:

• Diffusion of O₂ is directly proportional to the solubility of gas.
• If the solubility of a gas is more in the fluid medium, a large number of molecules are available or diffusion.
• So, diffusion also increases.

5. Molecular weight of the gas:

• Diffusion of gas is inversely proportional to its molecular weight.
• If the molecular weight is more the density is more and diffusion is less.

6. Diffusion coefficient:

• It is defined as a constant, which is the measure of a dissolved substance diffusing through the concentration gradient.
• It reduces when the molecular size of the diffusing substance is increased.
• Thus, the smaller molecules diffuses rapidly than the large ones.

Relation between diffusion and its factors: