When exposed to a cold environment a neonatal senses the reduced skin surface temperature and sense core body temperature. Information from these various sensors is procressed,including average temperature,rate of temperature change and size of the stimulated area. Clod stress results in the initiation of a series of reactions to increase heat production and decrease heat loss. In adult the most sinificant involuntory method of heat production is shivering or chemical thermogenesis to produce the needed heat. This process is initiated in the hypothalamus and teansmitted through the sympathetic nerous system, leading to the release of norepinephrine at the site of brown