Question

The capillaries around the air sacs take in ___and give off___.

• A. oxygen
• B. carbon dioxide

Answer 1

Air sacs:

1. There are a number of air sacs present inside the lungs and these air sacs are called alveoli.
2. Alveoli are present at the end of bronchioles.
3. Alveoli are the site of gaseous exchange between oxygen and carbon dioxide.
4. The surface of the alveoli is surrounded by a fine network of blood capillaries, which helps in gaseous exchange.
5. When oxygen-rich air is inhaled through the nose, it reaches the alveoli to be taken up by blood capillaries.
6. In exchange, carbon dioxide from the blood comes to the alveoli, and thus, carbon dioxide-rich air is exhaled.

Final answer: The capillaries around the air sacs take in oxygen and give off carbon dioxide.