The primary function of the skin in regulating body temperature involves mechanisms like vasodilation and perspiration. When the body temperature rises, blood vessels in the skin expand, allowing heat to dissipate more effectively into the environment. Meanwhile, sweat glands produce moisture that evaporates from the skin surface, further cooling the body. In contrast, when the temperature drops, blood vessels constrict to conserve heat. Thus, the skin acts as a critical interface between the body and external environment, maintaining homeostasis and ensuring optimal physiological functioning.