4-Gas Exchange Flashcards
atmospheric pressure
weight of gas molecules from gravity pulling towards earth
-dec as go higher, inc as closer to earth
-density of air less higher in atmos
760 mmHg
partial pressures
calculate by multiplying fractional concentration x atmos P
air is mostly nitrogren + some oxygen + others
daltons law
total P of a mixture of gases = sum of partial pressures of component gases
effect of water vapor on partial pressure
subtract water vapor P from total atmos P THEN multiply by fractional concentration
PH20 = 47 mmHg so 760-47
primary driving force of diffusion
pressure gradient
rate of diff = (cross section area x diffusion coefficient x pressure gradient) / thickness of membrane
partial pressure trends
O2 and CO2 diffuse downhill along gradients
-CO2 in oppo direction tho
henry’s law
solubility of gas in a liquid (oxy in blood) directly proportional to partial P of gas above liquid
-higher PP in lungs then higher in blood
aqeous gas = partial pressure gas x constant
gas exchange driven by what
diffusion and perfusion
pressures in dry inspired air
O2 = 160
CO2 = 0
pressures in humidified air trachea
O2 = 150
CO2 = 0
pressures of alveolar air
O2 = 100
CO2 = 40
alveolar capillary membrane
blood PCO2 equil rapidly unless heavy exercise so venous PO2 lower and blood flow faster
O2 diffusion to tissues
@ arterial capillary = 95/100
@ venous end = 40 mmg
tissue PO2 balanced by
oxygen consumption and delivery
-if inc consumption then dec PO2 if delivery not inc proportionally (exercise)
CO2 diffusion
arterial end capillary = 40 mmHg
tissue = 45 mmHg
venous end = 45 mmHg
