How does the integumentary system help regulate body temperature?

Keeping the body temperature constant is crucial for maintaining homeostasis. The integumentary system participates in thermoregulation in several ways.

Given the surface of the skin, the number of blood vessels in the dermis is vast. If the body has to get rid of excessive heat, an effective way to achieve this is increased blood flow through the skin. Vasodilation of so many blood vessels efficiently transfers heat from the internal tissues to the periphery (skin). From the skin, heat is further lost to the external environment. Heat is lost from the skin in three ways: by radiation, by the flow of air called convection, and by direct contact with another object called conduction. Heat always flows from the point of higher temperature to the point of lower temperature. Another way the skin regulates high temperatures is sweating. Sweat, made up mostly of water, covers the skin and evaporates, removing heat from the skin.

The opposite happens when the body has to conserve heat to maintain homeostasis. In this case, blood vessels' network in the skin constricts, blood flow is reduced and slowed down, so heat loss is prevented.

This strategy is not unlimited. If skin temperatures continue to drop to levels potentially dangerous to skin cells, blood vessels vasodilate, blood flow increases, and heat raises skin temperature. This increased blood flow is why the hands are red in the extreme cold after a while.