What is a primary function of the epidermis?

The primary function of the epidermis is to serve as a protective barrier for the body. It is the outermost layer of the skin and plays a critical role in preventing water loss from the underlying tissues, thus helping to maintain hydration and overall homeostasis. The epidermis achieves this through its structure, which includes multiple layers of cells, primarily keratinocytes that produce keratin, a protein that enhances the waterproofing capability. This functional aspect is vital in protecting the body against environmental threats such as pathogens, chemicals, and physical abrasions, in addition to regulating water retention.

While sweat glands, blood vessels, and other components of the integumentary system assist with heat regulation and immune response, these are not functions of the epidermis itself. The epidermis does not store fat, as adipose tissue is found deeper in the skin layers, specifically in the hypodermis or subcutaneous layer.