Principles of diffusion Flashcards
What factors affect alveolar ventilation?
Rate and depth of breathing
Airway resistance
Lung compliance
What is Henry’s law of dissolved gasses and its related equation?
The concentration of gas dissolved in a liquid is proportional to its partial pressure
Cx = K x Px
Where K is the solubility
What is the typical oxygen content in arteries?
95 mL
What is the typical oxygen content in veins?
40 mL
What is the typical CO2 content in veins?
46 mL
What is the equation related to Fick’s law?
D = (A/T) (Dc x deltaP x S)
Dc = diffusion coefficient
S = solubility coefficient
What factors determine pulmonary diffusion capacity?
Surface area of respiratory membrane
Thickness of respiratory membrane
Diffusion capacity of gas
Partial pressure of gas
Solubility of gas
Affinity of the gas with Hgb
What determines the partial pressure of a gas in fluid?
Dissolved gas, not by bound molecules
What does diffusion limited mean?
Gas does not reach the diffusion equilibrium between alveoli and capillaries
What does perfusion limited mean?
Gas does reach its diffusion equilibrium between alveoli and capillaries before the end of the capillary
What is the normal limiting of diffusion of O2?
Perfusion limited
What is the normal limiting of diffusion of CO2?
Perfusion limited
What is diffusing capacity?
The volume of gas that will diffuse through the membrane each minute for a pressure difference of 1 mmHg
What CO used to measure diffusing capacity of the lung?
Its uptake is diffusion limited
What is the normal value of DLCO?
25 mL/min/mmHg
