Question

The exchange of gases between which of the following is called external respiration?

• A. Lung alveoli and blood capillaries
• B. Lung alveoli and bronchi
• C. The buccal cavity and the external atmosphere
• D. Lung alveoli and pulmonary artery

Answer 1

The correct option is A Lung alveoli and blood capillaries

When the gaseous exchange occurs due to a difference in the partial pressure of gases between alveoli of lungs and capillaries it is termed as an external exchange as it involves air that ix either inhaled or exhaled from the environment outside the body while when the exchange occurs between capillaries and tissue it is known as the internal exchange.

So the correct option is 'Lung alveoli and blood capillaries'.