Skin's Anatomy - Function and How it Ages

Skin has 3 layers - the epidermis, dermis, and subcutaneous tissue

1. Epidermis: The Outer Layer of Skin and is visibly seen on the surface.  The epidermis is the thinnest of the layers and ironically the main barrier of protection for the entire body.  The thickness of the epidermis varies in different types of skin. It is the thinnest on the eyelids at .05 mm and the thickest on the palms and soles at 1.5 mm. The epidermis also contains the pigment melanin that gives skin its color. 

There are 5 delicate ‘sheets’ or layers of cells that make up the entire epidermis. From bottom (most internal) to top (most external) the layers are named:

- stratum basal
- stratum spinosum
- stratum granulosum
- stratum licidum
- stratum corneum

Approximately every 27 days new skin is regenerated through a process of skin cell turnover. The bottom layer (stratum corneum) of the epidermis is where new skin cells originate.

As cells are created they crowd and are pushed upward into the next higher layer. As the cells move into the higher layers, they flatten and eventually die. As old, dead skin cells they reach the outer surface, then they slough off replaced by the upward moving cells below them. 

2. Dermis: The middle layer underneath supporting the epidermis. The dermis is a complex matrix of blood vessels, hair follicles, and sebaceous (oil) glands.  The dermis also contains elastic fibers known as elastin and protein fibers called collagen, and fibroblasts “glue like” cells that synthesize collagen and elastin together to form skin’s elasticity, support, and suppleness.