partial pressure of oxygen when pressure is 420 Torr

Question

Find the partial pressure of oxygen when pressure is 420 Torr. find the saturation of hemoglobin in the blood as it leaves the lungs.

Answer 1

Hi Chris,

 

You will first need to know how much oxygen is available at sea level, which is 1 atm or 760 torr. When we go up in altitude, we decrease the amount of pressure and also available oxygen. The amount of oxygen at sea level is approximately 100 torr. 

 

We can set up a ratio:

 

(P of O₂)/420 torr = 100 torr/760 torr

 

From this we get, P of O₂ = 100 torr * 420/760 ~ 55.3 torr. 

 

From this answer, we have to look at the hemoglobin saturation curve (I found one here: http://physiologyplus.com/oxygen-hemoglobin-dissociation-curve-o2-hb-curve/) 

 

We draw a line up from 55.3 to the %saturation and we see that it is about 87%.