The P(O²) in the tissue cells is 40 mm Hg. The blood as it enters the surrounding systemic capillaries has a P(O²) of 95 mm Hg. Therefore, oxygen diffuses out of the systemic capillaries down its partial pressure gradient into the cells. What is the partial pressure of oxygen in the systemic capillaries?
1) 40 mm Hg
2) 95 mm Hg
3) 55 mm Hg
4) Cannot be determined