SF3 Exam 2 Diffusion

Question 1

What factors govern gas exchange?

Answer 1

Gradient in pressure

Thickness/properties of membranes

Surface area of alveolus

Question 2

What limits uptake of O2 in the capillaries?

What other gasses have this same limitation?

Answer 2

Perfusion limit

You must up the amount of blood flowing through because the gas equilibrates rapidly.

N20 and CO2

Question 3

Which gas is diffusion limited?

Answer 3

CO

Question 4

What variables does DLCO depend on? What is the relationship?

Answer 4

Area and thickness of capillary membranes

Direct to area

Inverse to thickness

Question 5

What does DLCO measure?

Answer 5

Conductance

Question 6

Why is DLCO low for an obstructive disease?

Answer 6

Alveolar simplification
Loss of pulmonary capillary structures

Basically loss of area

Question 7

Why is DLCO low for a restrictive disease?

Answer 7

Thick alveolar membrane that impairs diffusion

Question 8

What are instances where DLCO increases

Answer 8

Asthma
Exercise
Extreme obesity 
Intra-alveolar hemorrhage Left/Right Cardin shunt 
Polycythemia (increase of hemoglobin)

Question 9

What values do you look at when determining restrictive vs obstructive?

Answer 9

FRC, FEV/FVC, and DLCO