The partial pressure of oxygen in the blood returning to the lungs from the body is about
A) 80 mm Hg
B) 60 mm Hg
C) 40 mm Hg
D) 20 mm Hg

Question

Quizplus · Accepted Answer

The partial pressure of oxygen in the blood returning to the lungs from the body is about 40 mm Hg. This is because the oxygen has been used up by the body tissues and the blood is returning to the lungs with a lower partial pressure of oxygen. The partial pressure of oxygen in the lungs is higher (about 100 mm Hg) and this difference in pressure allows for oxygen to diffuse into the blood for transport to the body tissues.

The Partial Pressure of Oxygen in the Blood Returning to the Lungs