Which physiological response is commonly experienced during deep dives?

During deep dives, as divers are subjected to increased pressures, they often experience an increase in nitrogen absorption. This phenomenon occurs because the partial pressures of gases increase with depth, leading to a greater amount of nitrogen dissolving in the body tissues. If a diver ascends too quickly after a deep dive, this nitrogen can form bubbles in the bloodstream and tissues, resulting in decompression sickness, commonly known as "the bends." This condition can be very serious and is a critical consideration in dive planning and execution.

The other physiological responses listed, such as increased heart rate, decreased oxygen levels in the blood, and improved lung capacity, do not directly correlate with the immediate and hazardous effects observed due to deep diving and nitrogen absorption. Instead, they may occur under different conditions or be influenced by other factors in diving, but do not have the same degree of risk tied to deep dives as the increased nitrogen absorption does. Understanding the correlation between depth, pressure, and nitrogen absorption is essential for safe diving practices.