Which layer of skin is primarily responsible for temperature regulation?

The dermis is the layer of skin that plays a crucial role in temperature regulation. It contains a rich network of blood vessels and sweat glands. When the body temperature rises, these blood vessels can dilate (a process known as vasodilation), allowing more blood to flow through the skin's surface, where heat can be released into the environment. Additionally, sweat glands in the dermis produce sweat, which cools the body through evaporation when it reaches the skin's surface. These mechanisms make the dermis integral to maintaining a stable internal temperature.

The other layers, while important for various functions, do not primarily handle temperature regulation. The epidermis primarily serves as a protective barrier against the external environment, and the hypodermis (or subcutaneous layer), while providing insulation and a cushion for underlying structures, is not involved in active temperature regulation like the dermis. Therefore, the role of the dermis in facilitating blood flow and sweat production clearly establishes it as the layer responsible for temperature regulation.