Regulation of body temperature or thermoregulation is a negative feedback mechanism which aims at maintaining constant body temperature. Optimum body temperature for human is 370C.
Thermoregulation in hot condition
In hot condition, sweat glands increase sweating, superficial blood capillaries undergo vasodilation, erector muscles relax thus lower the hair, and endocrine glands decrease metabolic rate. These activities increase heat loss and decrease heat gain to maintain the optimum body temperature.
Thermoregulation in cold condition
In cold condition, sweat glands decrease sweating, superficial blood capillaries undergo vasoconstriction, erector muscles contract thus raise the hair, endocrine glands increase metabolic rate, and skeletal muscles contract involuntarily hence shivering. These activities decrease heat loss and increase heat gain to maintain the optimum body temperature.