RESP 120 Chapter 7: Gas Diffusion

What does Dalton’s Law state?

The total pressure of a gas mixture equals the sum of the partial pressures of each gas.

How do gases behave in a mixture according to Dalton’s Law?

Each gas acts independently as if it alone occupied the volume.

What percentage of barometric pressure is nitrogen?

~70%.

What percentage of barometric pressure is oxygen?

~21%.

What percentage of barometric pressure is argon?

~0.9%.

What percentage of barometric pressure is carbon dioxide?

~0.04%.

What is the alveolar gas equation for PAO₂?

PAO₂ = (PB − PH₂O) × FiO₂ − (PaCO₂ / R)

What is normal barometric pressure at sea level?

~760 mmHg.

What is the normal respiratory quotient (R)?

~0.8.

What is the A–a gradient equation?

A–a gradient = PAO₂ − PaO₂.

What is a normal A–a gradient in a young healthy adult?

5–10 mmHg.

How is the upper limit of normal A–a gradient estimated?

(Age ÷ 4) + 4.

In which direction does oxygen diffuse across the A-C membrane?

From alveoli to blood.

In which direction does carbon dioxide diffuse across the A-C membrane?

From blood to alveoli.

Why does CO₂ diffuse faster than O₂?

It is far more soluble, despite a smaller pressure gradient.

What law describes diffusion based on surface area, thickness, and pressure gradient?

Fick’s Law.

What law describes how much gas dissolves in a liquid?

Henry’s Law.

What law relates diffusion rate to molecular weight and solubility?

Graham’s Law.