Alveolar air equation

This is video 2 in a series on the Alveolar Air Equation that introduces the use of the equation itself. Examples are found in the next video
Ref:
1)John West Respiratory Physiology, The essentials
2)Egan's Fundamentals of Respiratory Care (9ed), Wilkins, Stoller and Kacmarek
3) Sibberson's Practical Math For Respiratory Care

[@remidesrosiers9830]

Is the 50 mmHg of O2 that left the alveoli used to oxygenate the venous blood?? I'm just a bit confused with where that oxygen goes

[@danger99danger]

You calculated the partial pressures of H2O, O2, and CO2 but not N2. Isn't nitrogen significant since it's ~79% of atmospheric air?

[@RespiratoryReview]

Nitrogen doesnt take part in gas exchange so it’s not as important as oxygen or co2 when it comes to the alveolar air equation. That being said it does have some important roles, such as splinting open the alveoli to maintain recruitment. If you wanted to calculate the partial pressure you would do it the same way as the others (760 x 0.78 = 592). Hope that helps!

[@Rene-uz3eb]

I don't get why the respiratory factor is in the equation. This is only a pressure equilibrium equation, no other quantitative factors. The alveoli don't need to know where the co2 is coming from.