Sweat glands become more active and secrete more sweat. Heat is lost through the evaporation of sweat on the surface of skin. Hair erector muscles in the skin relax so that the hair follicles are not erect. The flat hair increase the flow of air next to the skin and thereby increase heat loss by convection. Dilation of the arterioles in the skin and constriction of the shunt vessels allow more blood flow into the skin capillaries, thus increasing the heat loss. The metabolic rate in the body decreases , thus heat production in the body is reduced.