Diffusion of Gases

Question 0

Diffusion Limitation

Answer 0

When there is a non-existent partial-pressure gradient across a membrane, diffusion depends solely on the diffusivity of the compound

*CO follow this

Question 1

Fick’s Law of Diffusion

Answer 1

Vgas= ADP/T

D=diffusion constant
*CO2 and O2 => high diffusion constant

Question 2

Perfusion limitation

Answer 2

When the diffusivity of a compound is high, the driving force for diffusion is the partial pressure difference

*CO2, O2, and N20 follow this; only means for increasing perfusion is to increase the blood flow thru the pulmonary capillaries

Question 3

Diffusion-limited O2 perfusion

Answer 3

Occurs in pathologic conditions and strenuous exercise

Fibrosis will increased T

Question 4

Diffusion of CO2

Answer 4

Reaches equilibrium at the same time of O2 due to a lower partial pressure gradient

Question 5

Diffusing Capacity

Answer 5

DLx= Vx/ Pax-Pcx

Vx= Uptake of gas

Pax= alveolar pressure of x

*Usually, CO is measure because Pcx=O

Pcx= capillary pressure of x

Question 6

Conditions w/ Decreased DLco

Answer 6

Thickened Membrane (Sarcoidosis, Fibroses, Alveolar/Interstitial edema)

Decreased A (emphysema, Low CO)

Decreased RBC uptake (anemia, hypovolemia)

Ventilation-perfusion mismatch