External respiration involves the
A)movement of air into and out of the lungs.
B)diffusion of gases between the alveoli and the circulating blood.
C)exchange of dissolved gases between the blood and the interstitial fluid.
D)binding of oxygen by hemoglobin.
E)utilization of oxygen by tissues to support metabolism.

Question

Quizplus · Accepted Answer

External respiration refers to the exchange of gases (oxygen and carbon dioxide) between the environment and the body. This process occurs primarily in the lungs via the diffusion of gases between the alveoli (where gas exchange occurs) and the circulating blood in nearby pulmonary capillaries. Movement of air into and out of the lungs (choice A) is part of the process, but not the defining characteristic of external respiration. Exchange of dissolved gases between the blood and interstitial fluid (choice C) occurs during internal respiration. Binding of oxygen by hemoglobin (choice D) occurs in the lungs and is part of external respiration, but it is not the defining characteristic of the process. Utilization of oxygen by tissues to support metabolism (choice E) occurs during cellular respiration.

External Respiration Involves the