Question

The alveoli of the lungs do not contain ``air'' because

• A. We normally do not ventilate our lungs at a high enough rate.
• B. The lungs have too many alveoli to ventilate.
• C. There is ``dead space'' in the trachea and bronchi.
• D. The trachea and bronchi are too small in volume.

Hint:

\textbf{Dead space} refers to the air in respiratory passages where gas exchange does not occur.

Answer 1

The Correct Option is C

Step 1: The air that fills the alveoli is not fresh atmospheric air but a mixture of incoming air and residual air.
Step 2: The trachea and bronchi form the conducting part of the respiratory system.
Step 3: These conducting airways do not participate in gas exchange and are referred to as anatomical dead space.
Step 4: Due to the presence of dead space, part of the inhaled air remains in the trachea and bronchi and does not reach the alveoli.
Step 5: Hence, the alveoli never contain purely fresh air.