The Partial Pressure of Oxygen in the Interstitial Space of Peripheral

Question

The partial pressure of oxygen in the interstitial space of peripheral tissues is approximately
A) 40 mm Hg.
B) 45 mm Hg.
C) 50 mm Hg.
D) 70 mm Hg.
E) 100 mm Hg.

Accepted Answer

Oxygen diffuses from the capillaries into the interstitial space and then into the cells. The partial pressure of oxygen in the arterial blood is approximately 95 mm Hg, but it decreases as blood flows through the capillary network. By the time blood reaches the capillary beds in peripheral tissues, the partial pressure of oxygen has decreased to approximately 40 mm Hg. Therefore, choice A is the correct answer.