Which statement correctly describes the oxygen content of blood on the right versus left sides of the heart?

Which statement correctly describes the oxygen content of blood on the right versus left sides of the heart?

• A. The right side is high in oxygen and low in carbon dioxide; the left side is low in oxygen and high in carbon dioxide.
• B. The right side is low in oxygen and high in carbon dioxide; the left side is high in oxygen and low in carbon dioxide.
• C. Both sides have high oxygen content
• D. The right side oxygen content is independent of the left side

Answer: (B)

Blood returning from the body to the right heart is venous blood, which is low in oxygen and high in carbon dioxide. It goes to the lungs to be reoxygenated and to release CO2, and then the left heart receives blood that is rich in oxygen and low in CO2. From there, the oxygenated blood is pumped to the body. So the right side carries blood with low O2 and high CO2, while the left side carries blood with high O2 and low CO2. This is why the description matching that pattern is correct, reflecting the flow through the heart and lungs and the effect of pulmonary gas exchange.

Blood returning from the body to the right heart is venous blood, which is low in oxygen and high in carbon dioxide. It goes to the lungs to be reoxygenated and to release CO2, and then the left heart receives blood that is rich in oxygen and low in CO2. From there, the oxygenated blood is pumped to the body. So the right side carries blood with low O2 and high CO2, while the left side carries blood with high O2 and low CO2. This is why the description matching that pattern is correct, reflecting the flow through the heart and lungs and the effect of pulmonary gas exchange.