The role of the circulatory system in thermoregulation involves the distribution of heat throughout the body. Blood vessels can constrict or dilate to regulate blood flow, helping to maintain a stable internal temperature. For instance, when the body overheats, blood vessels dilate, increasing blood flow to the skin, allowing heat to escape. Conversely, when cold, blood vessels constrict to conserve heat, emphasizing the circulatory system's importance in temperature regulation.