text: Hypothermia is a dangerous drop in your body's core temperature. FROSTBITE is when your skin/tissue is damaged by cold. Basically, the water in your tissue freezes. Ice crystals damage/destroy tissue cells, and the cells die. If you get serious enough frostbite the skin turns black - meaning the tissue is dead. Which is why fingers and toes need to be amputated... to prevent the spread of gangrene.