PADI Divemaster Certification Practice Exam

What happens to nitrogen levels in the bloodstream as pressure increases?

1. Nitrogen is released from the bloodstream

2. Nitrogen dissolves into the bloodstream

3. Nitrogen levels remain unchanged

4. Oxygen replaces nitrogen in the bloodstream

The correct answer is: Nitrogen dissolves into the bloodstream

As pressure increases, nitrogen dissolves into the bloodstream due to the principles laid out in Henry's Law, which states that the amount of gas that dissolves in a liquid is proportional to the pressure of that gas above the liquid. When scuba diving, as a diver descends and experiences increased ambient pressure, nitrogen gas from the breathing gas (which is approximately 78% nitrogen) becomes more soluble in the bloodstream. This is significant because it increases the nitrogen levels in the body, meaning that as divers go deeper, they accumulate more nitrogen in their tissues, which can lead to decompression sickness if they ascend too quickly and the nitrogen gas comes out of solution too rapidly.