Respiratory 3 Flashcards
Gases, just like ions and water, move according to the principles of _____
diffusion.
After gas exchange in the pulmonary capillaries,PO2 is actually 95 mmHg due to ______
bronchial circulation.
After gas exchange in the pulmonary capillaries,PO2 is actually ___ mmHg due to bronchial circulation.
95 mmHg
______ refers to the pressure of one gas in a mix.
Partial Pressure (Pgas)
At normal alveolar ventilation and O2 absorption rates (250 ml/min), PAO2 is ____ mmHg.
100 mmHg
Increasing alveolar ventilation will ____ PAO2.
increase
To calculate a partial pressure in a liquid solution, the ____ and _____ of the gas are required
relative concentration and the solubility coefficient
This addition of water ______ the partial pressure of all other gases.
decreases
Attractability of molecules to water. If this number is high, the gas diffuses quickly.
Solubility Coefficient.
Henry’s Law–Partial Pressure =
PP= Concentration of Dissolved Gas/Solubility Coefficient
At a constant temperature, the amount of a gas that dissolves in liquid is ______ to the partial pressure and the solubility.
directly proportional
Gas Exchange at the Respiratory Membrane Depends on what 2 things?
- Transport rate through the respiratory membrane.
2. The rate of alveolar ventilation
An increase in alveolar ventilation will _____ PAO2 and gas exchange with an upper limit of 150 mmHg (the PAO2of humidified air.
Increase
What 3 factors increase the volume of gas diffusing through the tissue barrier per unit time?
- Difference in Partial Pressures Across the Membrane (ΔP )
- Solubility of Gas in Fluid (S)
- Cross-Sectional Area of Membrane (A)
What 2 factors decrease the volume of gas diffusing through the tissue barrier per unit time?
- Distance of Diffusion (d)
5. Molecular Weight of Gas (MW)
A tissue with high metabolic activity will have a ____ PO2, creating a ____ partial pressure gradient.
lower; larger
CO2 is ____ soluble (S) than O2so CO2 diffusion occurs ____ rapidly
more; more
If more pulmonary capillaries are recruited, as in exercise, the surface area (A) available for diffusion _____
increases
If the thickness of the diffusion barrier increases (d), such as with Pulmonary Fibrosis or Edema, this _____ diffusion.
decreases
What are the 6 components of respiratory membrane?
- Surfactant
- Alveolar Epithelium
- Alveolar Basement Membrane
- Interstitial Space
- Endothelial Basement Membrane
- Capillary Endothelium
Average width of respiratory membrane is ____ μm
0.6 μm
Under normal conditions, O2 transport into pulmonary capillaries is _____-LIMITED
PERFUSION-LIMITED
under other conditions (fibrosis, emphysema, strenuous exercise),O2 transport into pulmonary capillaries can become _____-LIMITED.
DIFFUSION-LIMITED
Measures respiratory membrane’s functional integrity; Amount of a gas entering pulmonary blood per unit time (ml/min/mmHg)
Diffusing capacity of the lung (DL)
DLCO2 cannot be calculated because of its ______
rapid diffusion
DLO2 is also difficult to calculate since most of O2 binds to ______
hemoglobin
______ is ideal for DL since it is diffusion-limited.
Carbon monoxide
Decreased Surface Area (A) or Increased Distance of the diffusion barrier (d), will ____ gas diffusion.
decrease
What 3 things could an abnormally low DLCO test indicate?
1. Thickening of the Barrier (increased d) –Interstitial edema or fibrosis 2. Decreased Surface Area (decreased A) –Emphysema –Low Cardiac Output –Tumors –Ventilation-Perfusion Mismatch 3. Decreased Uptake –Anemia –Decreased blood volume in pulmonary capillaries
- Thickening of the Barrier (increased d) can be caused by ____ or _____
–Interstitial edema or fibrosis
- Decreased Surface Area (decreased A) can be caused by what 4 things?
–Emphysema
–Low Cardiac Output
–Tumors
–Ventilation-Perfusion Mismatch
- Decreased Uptake can be caused by what 2 things?
–Anemia
–Decreased blood volume in pulmonary capillaries
Someone with a thickened alveolar membrane (pulmonary fibrosis) will have ____ limited oxygen transfer at rest and it will be an even more pronounced limitation with exercise
diffusion limited O2 transfer
Calculation of PAO2 is important because you can compare the value to PaO2. A large difference indicates a problem with diffusion.
A-a gradient
Normal A-a gradient is ___ mmHg in a young, non-smoker.
5-10
The A-a gradient increases by ___ mmHg for each decade so a normal value for a 40 year old would be
1; 14
A good estimate for a normal A-a gradient is (formula)
Age/4 + 4
PAO2 is predicted based on what 3 things?
- The partial pressure of O2 inspired
- The PaCO2
- The ratio of CO2 produced/O2consumed—the respiratory quotient
______ is the ratio of CO2 produced (200 ml/min) divided by the O2 consumed (250 ml/min)
Respiratory quotient (RQ)
