The lower the temperature, the more cold man. From the cold leather covered crawl, muscles are contracted and the person begins to tremble. Shiver is a mechanism for warming the body: the shiver is a muscle contraction, when the muscle is warm. In order not to freeze, the body begins to produce several times more heat than under normal conditions.
"Smart" human body tries to keep warm in the vital organs of the hands, feet and nose outflow of blood, which enters more important for the functioning of the body parts of the body.