PADI Divemaster Certification Practice Exam

What physiological effect can result from CNS oxygen toxicity?

1. Improved cognitive function

2. Enhanced physical performance

3. Seizures

4. Increased lung capacity

The correct answer is: Seizures

Central nervous system (CNS) oxygen toxicity is a condition that arises when a diver breathes oxygen at high pressures for extended periods. One of the significant physiological effects of this condition is the occurrence of seizures. This is due to an increase in the partial pressure of oxygen, which can lead to increased neuronal excitability and disruptions in normal brain function. At high oxygen levels, especially during deep dives or when using certain gas mixtures, oxygen can have toxic effects on the central nervous system. These effects may include visual disturbances, muscle twitching, and ultimately seizures, which can pose serious risks during a dive. Understanding this aspect of oxygen toxicity is crucial for divers and dive professionals, as it emphasizes the need to monitor oxygen exposure and adhere to depth and time limits to ensure safety. Other options, such as improved cognitive function or enhanced physical performance, do not occur as a result of CNS oxygen toxicity, and increased lung capacity is not a direct physiological effect related to oxygen toxicity. Instead, the primary concern is the adverse effects on brain function, of which seizures are a prominent and critical concern for divers.