Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
14 Cards in this Set
- Front
- Back
|
What determines movement of gas between gas and liquid phases?
|
Pressure gradients determine movement of gas irrespective of whether it is in gas or liquid phase?
|
|
|
How to calculate partial pressures? What are O2, CO2, N2 partial pressures?
|
Partial pressure = Atmospheric pressure x fraction.
O2= 160 CO2 =0 N2 = 600 |
|
|
What can henry's law be used for?
|
To find concentrations of gasses in a liquid.
|
|
|
What is the pathway of gas diffusion in the lung?
|
O2 starts in the alveolus, diffusing through the WATER and SURFACTANT in the alveoi -> alveolar epithelium -> epithelium basement membrane -> interstitial fluid -> capillary basement membrane -> capillary endothelium -> plasma
|
|
|
What factors determine diffusion of gasses in the lung?
|
1) those due to the diffusion process itself (thickness of membrane, surface area)
2) time it takes for O2 to react with Hb given by theta. |
|
|
What is the diffusion equation
|
D = (delta p x A x S) / (D X sqrt(MW))
|
|
|
How to estimate lung diffusing capacity?
|
Total amount of gas exchange/mean capillary gradient (alveolar - capillary content)
VO2/(PA - PC) For CO, VCO/PACO since capillary value 0. |
|
|
Does diffusion limitation affect PaCO2 and PaO2?
|
Yes but it affects PaO2 more because the limitations are due primarily to the diffusion process itself. The graphs illustrate that while CO2 takes longer than O2 to equilibrate in a healthy subject, CO2 can still equilibrate relatively well when diffusion is operating only at 25%. On the other hand, oxygen barely reaches equilibrium when diffusion capacity is at 25%.
The reason CO2 does not normally reach equilibrium as fast as O2 is due to complicated chemical reactions of CO2. |
|
|
How does exercise affect lung diffusion capacity?
|
Exercise increases lung diffusion capacity
|
|
|
How does hypoxia affect lung diffusion capacity?
|
Reduces lung diffusion capacity dt reduced driving pressure
|
|
|
How does emphysema affect lung diffusion capacity?
|
Emphysema reduces lung diffusion capacity dt reduced surface area
|
|
|
How does pulmonary fibrosis affect lung diffusion capacity.
|
Reduces diffusion capacity dt thickening alveolar capillary membranes.
|
|
|
How does high altitude residence affect lung diffusion capacity?
|
In childhood, lung growth is stimulated, resulting in increased alveolar capillary surface area to increase lung diffusing capacity.
|
|
|
How does O2 move from capillaries to the tissues?
|
This is a purely passive process (diffusion). As Hb moves more and more down the capillaries, it tends to decrease its affinity for O2, and this is the O2 that then passively diffuses into the tissues.
|
