The process of exchanging oxygen and carbon dioxide between the alveoli and the blood of the capillaries is called

The process of exchanging oxygen and carbon dioxide between the alveoli and the blood of the capillaries is called

• A. external respiration.
• B. alveolar ventilation.
• C. pulmonary ventilation.
• D. cellular metabolism.

Answer: (A)

External respiration is the process of gas exchange between the air in the alveoli and the blood in the pulmonary capillaries. It happens by diffusion across the thin alveolar–capillary membrane: oxygen moves from the alveolar air, where its partial pressure is higher, into the blood, while carbon dioxide moves from the blood, where its partial pressure is higher, into the alveolar air to be exhaled. This phase is distinct from alveolar ventilation or pulmonary ventilation, which describe the movement of air into and out of the lungs, and from cellular metabolism, which is the cellular use of oxygen to produce energy and CO2 as a waste product. Internal respiration is related but refers to diffusion of gases between the blood and body tissues.

External respiration is the process of gas exchange between the air in the alveoli and the blood in the pulmonary capillaries. It happens by diffusion across the thin alveolar–capillary membrane: oxygen moves from the alveolar air, where its partial pressure is higher, into the blood, while carbon dioxide moves from the blood, where its partial pressure is higher, into the alveolar air to be exhaled. This phase is distinct from alveolar ventilation or pulmonary ventilation, which describe the movement of air into and out of the lungs, and from cellular metabolism, which is the cellular use of oxygen to produce energy and CO2 as a waste product. Internal respiration is related but refers to diffusion of gases between the blood and body tissues.