ABSTRACT
The average adult skin surface area is 1.5 to 2.0 square meters; in a newborn, the skin surface area is 0.2 to 0.3 square meters. The epidermis and dermis together range in thickness from 1 to 2 mm. The epidermis can be 0.05 mm thick, as in the eyelid, to 1 mm thick, as in the soles of the feet. Skin is generally thicker in males than in females. It peaks in thickness at 30 to 40 years of age and then thins. The skin is derived from ectoderm and mesoderm. It has many important functions, such as protection, fluid/electrolyte homeostasis, and thermoregulation, as well as immunologic, sensory, and metabolic roles (e.g., vitamin D synthesis).
