Composition of Your Skin


Your Skin's Many Layers

Your skin is composed of three layers: 1) Epidermis, 2) Dermis, and 3) Hypodermis. Moreover, each layer is composed of sub–layers, each of which serve a different function.


The Epidermis layer is composed of four to five sub–layers, depending upon body location. The outermost two sub–layers of your skin are composed entirely of dead skin cells. It is within these two "dead cell" sub–layers where TanSome Sunless Tanning Lotion works. The tanning agents within TanSome self tanning lotion oxidize the keratin within these two sub–layers, gradually turning them dark bronze.


The remaining three sub–layers of the Epidermis, as well as the sub–layers of the Dermis and Hypodermis, are composed entirely of live skin cells. It is within these "live cell" sub–layers and layers where sun tanning / bed tanning occurs. A suntan, whether from the sun or tanning bed, is the result of damaged live skin cells. The UV–radiation from the sun / tannning bed penetrates into your live skin cells, driving melanin toward your skin's surface and darkening it. The darkening of your skin is a symptom of sunlight overdose. The darkening of your skin essentially turns it into a UV–light filter, minimizing future sunlight penetration.


An average adult has about 18–20 square feet of skin, which weighs about 6 pounds (as much as a laptop computer). The three layers of your skin are:


1) Epidermis Skin Layer

Your epidermis skin layer is composed of 4 to 5 layers, depending on the region of your body. These layers are described below, in descending order, from your skin's outermost layer inward (cross–section shown in right pane):

1.1) Cornified Layer

Also known as the "stratum corneum," it is the outermost layer of your skin. This layer is composed of envelopes filled with keratin, which is made up of dead cells that have migrated up from your inner skin. As these dead cells slough from your skin, they are continuously replaced by new cells. Every day, you shed millions of dead cells; shedding is accelerated by the scuffing of your clothes, bathing, exfoliating, shaving, perfuming, etc.


Cornified Layer cells contain keratin, a protein that helps keep your skin hydrated by preventing water evaporation. These cells can also absorb water, further aiding in hydration. Additionally, this layer is responsible for the "spring back" or stretchy properties of your skin.


When the tanning agents within TanSome Sunless Tanning Lotion combine with the keratin, the keratin oxides and forms a chemical compound known as melaninoids. The melanoids turn either orange or brown in color, depending upon the ingredients used to carry the tanning agents into your skin, and the time required to tan (Sunless Tanning – Instant vs Gradual). They turn orange if the tanning time is short (instant tanning) and brown if the tanning time is long (gradual tanning). Also, the natural ingredients within TanSome Sunless Tanning Lotion (tropical oils and butters, antioxidants, and vitamins) assist in transporting the tanning agents throughout the Cornified Layer.


Cornified Layer thicknesses vary according to the amount of protection and/or grip required by your body's region. Your hands are used to grasp objects, requiring your palms to be covered with a thicker layer. The soles of your feet are prone to injury, so they are protected with a thicker layer, too. In general, this layer contains 15 to 20 layers of dead cells, and has a thickness between 10 and 40 microns (your head hair diameter is about 80 microns). These dead cells were live cells about 30 – 60 days earlier, depending upon your age.


1.2) Clear/Translucent Layer

Also known as the "stratum lucidum," this skin layer is found throughout your body, but is the thickest on your palms and the soles of your feet. This layer is located between your Granular Layer and your Cornified Layer. It is composed of three to five layers of dead, flattened keratinocytes. The thickness is controlled by the rate of mitosis (cell division) of the epidermal cells. Additionally, melanocytes determine the darkness of your Clear/Translucent Layer, and the color of your skin.


1.3) Granular Layer

Also known as the "stratum granulosum," it is a skin layer found between your Cornified Layer and Spinous Layer. In this layer, keratinocytes, responsible for the manufacture of keratin, account for 95% of all your skin cells. Keratohyalin within the keratinocytes, aggregate and cross–link your keratin fibers. Within the keratinocytes are also Lamellar Granules, which form into keratinosome, which provides protection of your skin from its environment.


1.4) Spinous Layer

Also known as the "stratum spinosum," it is a skin layer found between your Granular Layer and your Basal/Germinal Layer. The presence of lipids in your Granular Layer creates a hydrophobic barrier (water repellant) between your Granular Layer and your Clear/Translucent Layer that prevents dehydration. Keratinization begins in your Spinous Layer.


1.5) Basal/Germinal Layer

Also known as the "stratum basale/germinativum," it is the deepest of the 5 layers of the epidermis. Your Germinal Layer is a continuous layer of cells. It is often described as one cell thick, though it may be two to three cells thick.


The basal cells of the Germinal Layer can be considered the "stem cells of the epidermis." They are undifferentiated and they proliferate. They create "daughter" cells that migrate superficially, differentiating as they do so. The keratinocytes of your Germinal Layer undergo mitosis (cell division) continually throughout your life.


Melanocytes, the pigment producing cells of your skin, are primarily found in your Germinal Layer.



2) Dermis Skin Layer

Your second layer of skin is the dermis, which contains the structural elements of your skin, the connective tissue. There are various types of connective tissue with different functions. For example, collagen gives your skin its strength, proteins called glycosaminoglycans give your skin its rigidity and maintains its overall shape; elastin fibers give your skin its elasticity.


Dermal–Epidermal Junction

The junction between your dermis and your epidermis is an important structure. The dermal–epidermal junction interlocks forming fingerlike projections called "rete ridges." The cells of the epidermis receive their nutrients from the blood vessels in the dermis. Your rete ridges increase the surface area of the epidermis that is exposed to these blood vessels and the needed nutrients.


3) Hypodermis Skin Layer

Your bottom layer of skin is the hypodermis layer (also known as the Subcutaneous Fat Layer), which contains fat cells. These fat cells provide insulation to the body and make the skin look plump or full. Healthy habits will bring this tissue into its optimal health, which will help your skin's overall health.