Which layer of skin regulates body temperature and houses hair follicles and nerve endings?

The dermis is the middle layer of skin that plays a crucial role in regulating body temperature and contains various structures essential for overall skin function. It is home to hair follicles, which produce hair and can aid in temperature regulation through mechanisms like piloerection (the raising of hair in response to cold or fear).

In addition to hair follicles, the dermis houses sweat glands, blood vessels, and nerve endings, all of which collectively contribute to thermoregulation. During heat exposure, sweat glands produce sweat that evaporates and cools the skin. Blood vessels can also dilate to release heat when the body is too warm. Conversely, when cold, blood vessels constrict to conserve heat.

The other layers of skin have different functions: the hypo dermis (subcutaneous) primarily acts as an insulator and energy reserve; the epidermis is the outermost layer that offers protection and does not house hair follicles or blood vessels; and the subcutaneous layer is more about fat storage and connection to underlying tissues, rather than temperature regulation. Thus, the dermis is the correct answer as it encompasses the critical elements for regulating body temperature while supporting hair follicles and sensory nerve endings.