The hypothalamus, which provides the highest level of endocrine control, integrates the activities of the nervous and endocrine systems.
The hypothalamus plays an important role in regulating the body temperature. This function is carried out by the anterior hypothalamus and the posterior hypothalamus. They have directly opposite effects.
Stimulation of the anterior hypothalamus begins a thermolytic response thereby resulting in decrease in the body temperature. While stimulation of the posterior hypothalamus begins a thermogenic response that leads to elevation in body heat and its conservation.
Thermolytic responses are characterized by cutaneous vasodilation which is illustrated by body reactions like elevation in heat loss by radiation, perspiration that facilitates heat loss by evaporation, and the typical feature of panting in animals particularly in dogs.
Thermogenic responses incorporate cutaneous vasoconstriction that results in minimizing loss of heat via radiation, the mechanism of shivering that increases heat level owing to vigorous muscular activity.
The hypothalamus is also well equipped to gauge the fluctuations in the temperature of the blood circulating within the body and so will respond.