Which term describes perfusion: exchange of oxygen and carbon dioxide between circulating blood and tissue cells?

Which term describes perfusion: exchange of oxygen and carbon dioxide between circulating blood and tissue cells?

• A. Diffusion
• B. Perfusion
• C. Ventilation
• D. Eupnea

Answer: (B)

Gas exchange at the tissue level occurs by diffusion—the movement of oxygen from higher to lower partial pressure from the capillary blood into tissue cells, and carbon dioxide in the opposite direction from tissues into the blood. Perfusion refers to the flow of blood delivering oxygen to tissues and removing waste, which makes diffusion possible but is not the exchange mechanism itself. Ventilation is the act of moving air in and out of the lungs, and eupnea means normal breathing. Therefore, the term for the actual exchange between circulating blood and tissue cells is diffusion.

Gas exchange at the tissue level occurs by diffusion—the movement of oxygen from higher to lower partial pressure from the capillary blood into tissue cells, and carbon dioxide in the opposite direction from tissues into the blood. Perfusion refers to the flow of blood delivering oxygen to tissues and removing waste, which makes diffusion possible but is not the exchange mechanism itself. Ventilation is the act of moving air in and out of the lungs, and eupnea means normal breathing. Therefore, the term for the actual exchange between circulating blood and tissue cells is diffusion.