Skin physiology

This review article offers a brief overview of skin physiology, including the epidermis, dermis, basement membrane zone and the role of psychological stress. Skin is the largest organ; it is complex and multifunctional, containing many specialized cells that are adapted to different functions. Skin consists of a superficial layer (epidermis) that adheres closely to the deeper layer (dermis) via the basement membrane. Loose connective tissue and fat underlie the dermis. The epidermis is composed of stratified squamous epithelium, comprising layers of closely packed cells produced by cell division of the ‘basal’ cell layer (a single sheet of columnar cells at the lowest level of the epidermis). The dermis lies below the epidermis and supports it structurally and nutritionally. The basement membrane zone forms an adhesion complex between the dermis and epidermis, providing support for the basal cells to allow growth, multiplication and migration, and allowing nutrients and cells to cross from the dermis. Psychological stress may precipitate or aggravate chronic disorders of the skin.