How are frostbites caused?

Frostbite is caused when the body is put under extremely cold conditions, when This happens the body withdraws blood from the less important parts of the body such as the fingers or the nose. This is done to keep the main organs of the body warm so that cardiac arrest can be avoided. The parts of the body from which the blood is taken from rot, and have to be amputated at a later stage. The more blood the main organs need the bigger the part from which the blood is taken from. This means that if put under the right conditions for long enough, a whole leg or arm could be removed.