Question

If a respiratory surface dries out, gas exchange will

• A. Increase
• B. Decrease
• C. Stop
• D. Not be affected

Answer 1

The correct option is B Decrease

The respiratory surface needs moisture for maximum efficiency. Oxygen from the air dissolves in the water on the surface momentarily and this allows the oxygen more time to cross the alveolar membrane. If the surface dries out, gas exchange will happen at a very reduced rate since fast-moving gaseous oxygen molecules do not efficiently cross the alveolar membrane. The reduced gas exchange is mostly likely not enough to support blood oxygenation for vital functions.

Therefore, the correct answer is option B.