Which of the Following Statements About Partial Pressures of Gases

Question

Which of the following statements about partial pressures of gases is TRUE?
A) PO2in blood is greater than PO2in tissues; PCO2in blood is greater than PCO2in tissues
B) PO2in blood is greater than PO2in tissues; PCO2in blood is less than PCO2in tissues
C) PO2in blood is greater than PO2in tissues; PCO2in blood = PCO2in tissues
D) PO2in blood is less than PO2in tissues; PCO2in blood is less than PCO2in tissues
E) PO2in blood is less than PO2in tissues; PCO2in blood is greater than PCO2in tissues

Accepted Answer

The statement "P_O2 in blood is greater than P_O2 in tissues; P_CO2 in blood is less than P_CO2 in tissues" is true. This is because oxygen diffuses from an area of higher partial pressure to an area of lower partial pressure, so the partial pressure of oxygen is higher in the lungs and blood than in the tissues. Conversely, carbon dioxide diffuses from an area of higher partial pressure to an area of lower partial pressure, so the partial pressure of carbon dioxide is higher in the tissues than in the lungs and blood.