How does the integumentary system help regulate an increase in body temperature?

The integumentary system plays a crucial role in thermoregulation, which is the process the body uses to maintain a stable internal temperature. When body temperature rises, the primary response involves the dilation of blood vessels near the surface of the skin, a process known as vasodilation. This allows more blood to flow to the skin's surface, where heat can be dissipated into the environment.

At the same time, sweat glands become activated, leading to increased perspiration. Sweat evaporates from the skin surface, which helps cool the body down as it absorbs heat from the skin during the phase change from liquid to vapor. This dual action of vasodilation and sweating effectively reduces body temperature.

The other options refer to mechanisms that do not contribute to cooling the body during an increase in temperature. Constricting blood vessels serves to retain heat, increasing metabolic rates would generate more heat rather than dissipate it, and producing more melanin is related to skin pigmentation and does not play a role in thermoregulation. Thus, the correct understanding of how the integumentary system regulates body temperature in response to heat is accurately captured in the correct response, which highlights the role of blood vessel dilation and sweat gland activation.