PADI Divemaster Certification Practice Exam

What is the physiological basis for nitrogen absorption during a dive?

1. It occurs uniformly in all tissues

2. It depends on the diver’s metabolic rate

3. It varies with blood flow and solubility

4. It is primarily controlled by lung capacity

The correct answer is: It varies with blood flow and solubility

The physiological basis for nitrogen absorption during a dive is most accurately described by the variation with blood flow and solubility. When a diver descends, the increased pressure affects how nitrogen is absorbed by the body tissues. Different tissues absorb nitrogen at different rates based on their blood flow and their ability to dissolve nitrogen. Well-perfused tissues, such as the brain and muscles, absorb nitrogen more quickly due to higher blood flow, while less perfused tissues, like fat, absorb it more slowly. Additionally, tissues have different solubilities for nitrogen, which means that they can hold and store varying amounts of nitrogen under the increased pressures experienced during a dive. This variability is crucial for understanding how to manage the risks of diving, particularly in relation to decompression sickness, as divers need to consider the varying levels of nitrogen saturation in their bodies. Other aspects, such as metabolic rate and lung capacity, play roles in diving physiology, but they do not directly describe the fundamental variations in nitrogen absorption across different tissues as pressure increases during a dive.