The organ that helps regulate body temperature is the skin. The skin acts as a barrier and plays a crucial role in thermoregulation through sweat production and blood flow adjustments. When the body temperature rises, sweat glands release moisture onto the skin's surface, which cools the body as it evaporates. Conversely, in cold conditions, blood vessels constrict to reduce heat loss, and the body may initiate shivering to generate warmth. This vital function maintains a stable internal environment for overall health.