AEMCA Practice Exam

What causes decompression sickness in divers?

1. Nitrogen bubbles collecting in tissues

2. Oxygen toxicity

3. Carbon monoxide buildup

4. Hypothermia from water temperatures

The correct answer is: Nitrogen bubbles collecting in tissues

Decompression sickness, often referred to as "the bends," occurs when divers ascend too quickly after spending time under pressure in the water. While they are diving, divers breathe air or a gas mixture that contains nitrogen, which is absorbed into their body tissues under higher pressure. As a diver ascends, the surrounding pressure decreases. If the ascent is too rapid, nitrogen that has been absorbed during the dive does not have enough time to be expelled safely through exhalation. Instead, nitrogen forms bubbles in the tissues and bloodstream, leading to various symptoms such as joint pain, dizziness, or more severe complications depending on the amount of nitrogen and where bubbles form in the body. In contrast, oxygen toxicity can occur at high pressures due to elevated levels of oxygen, impacting the nervous system, particularly during deep dives, but it is not the primary cause of decompression sickness. Carbon monoxide buildup is related to poor breathing gas or environmental conditions rather than the mechanics of ascent. Lastly, hypothermia arises from prolonged exposure to cold water but does not directly relate to the physiological effects of ascent and decompression. Thus, the formation of nitrogen bubbles in tissues during a rapid ascent is the fundamental cause of decompression sickness in divers.