What is the actual physical cause of decompression sickness?

The correct answer focuses on the concept of bubble formation and growth as the primary physical cause of decompression sickness (DCS). Decompression sickness occurs when a diver ascends too quickly after a dive, leading to a decrease in pressure surrounding them. Under high pressure, nitrogen, which is absorbed into the body during the dive, dissolves in the tissues and blood. When the pressure decreases too rapidly during ascent, the dissolved nitrogen can come out of solution, forming bubbles.

These bubbles can obstruct blood flow and cause a variety of physiological problems. They can also grow in size due to the difference in pressure between the tissues and the surrounding environment, leading to further complications. Therefore, the focus on bubble formation and growth accurately describes the mechanism of DCS as it emphasizes both the initiation of bubbles from decompressed nitrogen and their potential to expand, causing damage and symptoms associated with the condition.

This understanding is crucial for divers as it highlights the importance of controlled ascent rates and proper decompression stops to allow nitrogen to safely escape from the body without causing harmful bubble formation.