Diffusion

Question 1

which gases are limited by perfusion?

Answer 1

Co2
NO2
O2

Question 2

Which gases are diffusion limited?

Answer 2

CO

and O2 in dz states

Question 3

What is unique about perfusion limited gases?

Answer 3

They gases that need to equilibrate across the blood gas barriers
- no or limited reaction with Heme takes place

Question 4

The diffusion process is challenged by what?

Answer 4

Hypoxia
Thickening of the barrier
Exercise

Question 5

What is one good example of demonstrating diffusion difficulties of O2?

Answer 5

High altitude exercise

- the end capillary PO2 will not have reached equilibrium

Question 6

What happens to the pulmonary capillaries during exercise?

Answer 6

They recruit more
They dilate
- unless hypoxic in which they constrict and shunt

Question 7

What are the 2 stages of O2 loading? Called what?

Answer 7

1. Diffusion of the gas from alveolar to plasma through RBC membrane
2. Reaction of the heme

Diffusion resistance

Question 8

What is one way to decrease the heme reaction rate with CO? Why?

Answer 8

Give Pure O2

- Competes for Hemoglobin binding sites