Sweat glands become less active and sweat stops being produced. Hair erector muscles on the skin contracr, lifing the hair follicles upright to trap heat. Constriction of the arterioles in the skin and dilation of the shunt vessels result in less blood flow into the skin capillaries, thus decreaseing the heat loss. Sometimes, shivering(contraction of the skeletal muscles) occurs to increase heat production. The metabolic rate in the body increases, thus heat production in the body is increased.