Normal skin has a pH of 4.5 to 5.5 and is composed of three layers:
§     Epidermis (barrier to the outside world)

§ Dermis (accounts for skin’s strength and elasticity)

§ Subcutaneous Fat layer (provides insulation and cushion)

Epidermis: Composed mainly of protein rich Keratinocytes (80% to 90%) and Melanocytes (10%), measures 0.04 to 1.5 millimeters thick (thinnest area is the eyelids, thickest is the back and soles of feet), contains NO blood vessels, therefore is very dependant on diffusion, and is composed of three principal layers:

1)      Stratum Corneum – The barrier layer, is composed of dead Keratinocytes

      (Corneocytes).

2)      Granular/Spinous – Keratin (protein) fibrils become more plentiful as part of    

       the interior of the Kertinocyte.

3)      Basal – Where Kertinocytes divide, mature, and begin their 40 day migration

to the surface where they are ultimately exfoliated.  Melanocytes are present in the Basal layer.            

Dermis: Composed mainly of fibrous tissue (collagen and elastin), extra cellular matrix (GAGs), blood and lymphatic vessels, fibroblasts, measures between 0.5 and 1.0 millimeters in thickness, acts as the Matrix supporting and nourishing the Epidermis, and is divided into two layers:

1)      Papillary Dermis – contains fibroblasts, blood and lymphatic vessels, and is in

immediate contact with the Basal layer of the Epidermis providing the input of nourishment and the removal of waste through diffusion.

2)      Reticular Dermis – responsible for the amazing pliability and strength of the

skin.     

Subcutaneous Fat. Composed of fatty tissue, blood vessels, nerve endings, lymph vessels, and adnexal structures (hair follicles, sweat glands, sebaceous glands, etc…).