External respiration refers to gas exchange between which structures?

Prepare for your Anatomy and Physiology II Exam with our comprehensive exam resources. Utilize flashcards, multiple choice questions with hints, and detailed explanations. Boost your readiness for success!

Multiple Choice

External respiration refers to gas exchange between which structures?

External respiration is the diffusion of respiratory gases between the air in the lungs and the blood in the pulmonary capillaries. In the alveoli, oxygen moves from the inhaled air into the blood, while carbon dioxide moves from the blood into the alveolar air to be exhaled. This exchange occurs across the thin alveolar–capillary membrane driven by differences in partial pressures of O2 and CO2. This is different from internal respiration, which is the exchange of gases between the blood and body tissues, and from cellular respiration, which is the use of O2 within cells to produce energy. The idea of gas exchange occurring in the trachea isn’t correct, because the trachea is a conducting air passage without the thin walls and capillaries needed for diffusion.

External respiration is the diffusion of respiratory gases between the air in the lungs and the blood in the pulmonary capillaries. In the alveoli, oxygen moves from the inhaled air into the blood, while carbon dioxide moves from the blood into the alveolar air to be exhaled. This exchange occurs across the thin alveolar–capillary membrane driven by differences in partial pressures of O2 and CO2.

This is different from internal respiration, which is the exchange of gases between the blood and body tissues, and from cellular respiration, which is the use of O2 within cells to produce energy. The idea of gas exchange occurring in the trachea isn’t correct, because the trachea is a conducting air passage without the thin walls and capillaries needed for diffusion.

More practice questions