Regulating the body temperature happens through the process of thermoregulation. One system that is responsible for this is the excretory system. This process is an example of negative feedback. The body temperature tends to fluctuate within a normal range. So, the brain's control system and other parts of the body monitor this fluctuation and react to deviations from homeostasis.
The circulatory system is composed of blood vessels, including arteries, veins, and capillaries that are capable of dilation and constriction in order to help the body maintain its homeostasis. This system is also an example of negative feedback