Why do professional divers fear the bends?

Decompression. Deep diving causes nitrogen to dissolve in blood and creates bubbles in blood in coming up. The bubbles in blood cause damage in various organs including brain, spinal cord and bones. Blockage of blood vessels in the bones caused bone necrosis and pain. The term bends comes form similarity to a dance move that people with bone infarcts tend to have.
The Bends. Decompression sickness (dcs) is also called the bends. When a diver descends in the water- pressure increases. As the diver ascends there is less pressure which allows dissolved gas to form bubbles in body tissues. This can cause a variety of different symptoms ; in some cases can lead to death. It could also occur in an unpressurized aircraft going to high altitude, if a halo parachutist does not.