Respiratory III Flashcards
(47 cards)
why is PO2 in the pulmonary capillaries after gas exchange 95mmHg
because of bronchial circulation
what is the partial pressure of a gas
the pressure of one gas in a mix of gases
what is the formula for partial pressure of a gas
Patm x fractional concentration of a gas
what is atmospheric gas partial pressures
600mmHg nitrogen and 160 mmHg oxygen
what is the partial pressure of water in the lungs
47mmHg
what is the result of the generation of a partial pressure of water in the lungs
air is humidified and decreases the partial pressure of the other gases
what is the partial pressure of O2 in the lungs
149 mmHg
at normal alveolar ventilation and O2 absorption rates what is PAO2
100mmHg
what does increasing alveolar ventilation do to PAO2
increase it
what is the solubility coefficient
attractability of molecules to water
what does the solubility coefficient tell you if it is high
the gases diffuse quickly
what is henrys law
partial pressure = concentration of dissolved gases/solubility coefficient
which is more soluble: CO2 or O2
CO2
what is the formula for concentration of dissolved gas
= solubility coefficient x partial pressure
what does gas exchange at the respiratory membrane depend on
-transport rate through the respiratory membrane
-the rate of alveolar ventilation
what does an increase in alveolar ventilation do to PAO2 and gas exchange
increases both with an upper limit of 150 mmHg
what does transport through the respiratory membrane depend on
-difference in partial pressures across the membrane
- solubility of gas in fluid
-cross sectional area of membrane
- distance of diffusion
-molecular weight of gas
what is the formula for volume of gas diffusing through the tissue barrier per unit time
V = change in pressure x A x S/ (d X square root of MW)
what will be the PO2 of a tissue with high metabolic activity
lower PO2
which diffuses more rapidly: O2 or CO2
CO2
if more pulmonary capillaries are recruited what happens to surface area for diffusion
it increases such as converting from zone 2 to zone 3
what does an increase in thickness of the diffusion barrier do to diffusion
decreases it
what are the components of the respiratory membrane
-surfactant
-alveolar epithelium
-alveolar basement membrane
-interstitial space
- endothelial basement membrane
- capillary endothelium
under normal conditions, O2 transport into pulmonary capillaries is _____
perfusion limited
