PADI Divemaster Certification Practice Exam

What causes gas narcosis, and what symptoms are commonly observed?

1. It results from dehydration; symptoms include headaches

2. It results from rapid ascent; symptoms include severe pain

3. It results from gas blocking nervous system signals; symptoms include slowed thinking and euphoria

4. It results from high altitude; symptoms include dizziness and confusion

The correct answer is: It results from gas blocking nervous system signals; symptoms include slowed thinking and euphoria

Gas narcosis, often referred to as "nitrogen narcosis," occurs when divers descend to significant depths, and the increased pressure causes gases dissolved in the blood, particularly nitrogen, to exert a narcotic effect on the central nervous system. As the partial pressure of nitrogen increases, it can interfere with the normal functioning of nerve pathways, leading to a range of neurological symptoms. The symptoms that are commonly observed include slowed thinking, impaired judgment, a general sense of euphoria, and alterations in perception. Divers under the influence of gas narcosis might find that their ability to process information and respond appropriately to their surroundings is diminished, which can pose significant safety risks. Additionally, divers may experience a sense of well-being or light-headedness, contributing to a disorienting and potentially dangerous situation if not managed properly. Other potential answer choices allude to causes and symptoms that do not align with the physiological effects of gas narcosis. For example, dehydration and rapid ascent are not the primary causes of this condition, and the symptoms listed in those choices do not accurately reflect the specific effects that divers experience when subjected to higher pressures and the resultant narcotic influence of nitrogen.