Question

The exchange of gases between the air and blood takes place across the walls of the _________.

Answer 1

Exchange of gases/Breathing:

1. The process, by which air is drawn in from the atmosphere into the lungs and forced out from the lungs back into the atmosphere is known as breathing.
2. The respiratory system in humans includes the nose, pharynx, larynx, trachea, bronchi, alveoli and the lungs.
3. Alveoli are the tiny air sacs present in the lungs. It is the actual site of the respiratory system where the exchange of gases takes place.
4. The walls of the blood capillaries and alveolus are extremely thin, so the molecules of gases can easily pass through it.
5. Thus, oxygen diffuses into the blood from the alveoli and carbon diffuses out from the blood capillaries into the alveolus.

Final answer:
The exchange of gases between the air and blood takes place across the walls of the alveoli.