ANATOMY

Detailed explanation-1: -During gas exchange oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs. This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli.

Detailed explanation-2: -These pulmonary capillaries create the respiratory membrane with the alveoli. As the blood is pumped through this capillary network, gas exchange occurs.

Detailed explanation-3: -The correct answer: The exchange of gases between the alveoli and the blood capillaries is called external respiration.

Detailed explanation-4: -A high oxygen concentration in the alveoli and low oxygen concentration in the capillaries causes oxygen to move into the capillaries. A high carbon dioxide concentration in the capillaries and low carbon dioxide concentration in the alveoli causes carbon dioxide to move into the alveoli.