Lecture 24: Pulmonary Gas Exchange Flashcards
Which gas is most abundant in the atmosphere?
Nitrogen
Dalton’s Law
Total pressure exerted by non-reactive gases = sum of individual partial pressures
Boyle’s Law
Pressure and Volume are inversely proportional for an ideal gas at a fixed temperature
Henry’s Law
Volume of liquid is directly proportional to partial pressure of gas with that liquid at constant temperature
Ideal Gas Law
P = nRT/V
What happens to partial pressures when water vapor is added to the atmosphere?
Air is humidified/gas is added causing partial pressures to decrease
Relate the solubility coefficient to the partial pressure
partial pressure = [dissolved gas]/solubility coefficient
Which is more soluble in water, CO2 or O2? What does this mean for partial pressure?
CO2 is much more water soluble, but would have a much lower partial pressure than O2
What factors affect the rate of gas diffusion in a fluid?
Cross sectional area of fluid, molecular weight, solubility of gas in fluid, distance to which gas must travel, temperature of fluid
Why doesn’t alveolar ventilation increase above 149 mm Hg?
Because 149 mmHg is the maximum PO2 in the atmosphere
Va/Q Ratio
Ventilation perfusion ratio where Va=ventilation of alveoli and Q=blood flow in alveoli
What happens to the Va/Q ratio during an airway obstruction?
Va/Q=0 because Va=0; blood/gas content remains unchanged
What happens to the Va/Q ratio during a vascular obstruction?
Va/Q=infinity because Q=0; creates a physiologic shunt
Shunted blood
deoxygenated blood
The thin descending loop of Henle is highly permeable to which of the following?
A. Sodium
B. Water
C. Urea
D. Amino Acids
B. Water
