The First Step to Skincare

The First Step to Skincare

by Michael Caswell, Ph.D.

How often does a client come into your tanning salon and ask you to recommend a lotion or skincare product? As a salon owner, you are the gatekeeper for skincare products for your clients. The products you choose to market in your salon are based on your skincare knowledge and product performance. Your customers rely on your expertise in skincare and your product knowledge to match their needs with the correct products. If you fail to satisfy their needs, they will seek skincare help elsewhere.

Gaining Knowledge

The first step to becoming a skincare expert is to gain an understanding of the biochemistry and physiology of the skin. This includes knowledge of the various layers of the skin and their functions. The three layers of skin include the subcutaneous layer, the dermis and the epidermis. Each layer has a distinct function and purpose.

The Subcutaneous Layer

The subcutaneous layer is the innermost layer of skin and is simply a layer of fatty tissue that provides insulation against changes in temperature and stores energy for future use.

Dermis

The dermis contains a mixture of connective tissue and a variety of cells involved with dermal structure, immunology, nutrition, touch and many other events. It is the outermost layer of skin and contains capillaries to carry blood and nutrients to the skin. In addition, with collagen and elastin, the dermis also provides elasticity or stretch to the skin. The dermis also absorbs much more UVA than UVB. Approximately 5 percent of UVA radiation reaches the deepest layer of the dermis; however, about 5 percent of UVB reaches the outermost layer of the dermis.

Epidermis

The epidermis provides a barrier between the person and the outside world, so it is the first line of defense against any type of environmental insult. The epidermis is composed of four distinct layers of skin cells: stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. Each of these epidermal layers has a distinct function. The changes that occur in the cells as they move from the stratum basale to the stratum corneum are called differentiation.

Stratum Basale

The stratum basale or basal layer is located at the innermost layer of the epidermis, attached to the basement membrane. The basement membrane is a thin layer of material that separates the dermis from the epidermis and acts as an attachment site for some cells in the epidermis. The basal layer contains one layer of cells that constantly reproduce to make new skin cells. As the basal cell makes a new skin cell, the process of replacing the epidermis begins. This cell, like millions of other cells, slowly will progress outward to the surface of the skin. Eventually, the outermost cells will be shed, or sloughed.

Stratum Spinosum

The stratum spinosum, or spiny layer, contains as many as 30 layers of cells. This layer is the first step in the process of differentiation, as it is in the stratum spinosum that cells make and store proteins and lipids. The cell will use these materials later when it arrives at the outermost layer of skin.

Stratum Granulosum

The cell continues to move farther outward into the stratum granulosum, or granular layer. In the granular layer, which is about two cell layers thick, the cell loses its DNA which is chewed up by enzymes and reabsorbed into skin cells that can use the digested DNA. Because the cell no longer has DNA, it is considered dead.

The skin cell continues to change even after its demise. Its lipids change to support the barrier properties of the stratum corneum and give the cell flexibility. Its proteins change to create an infrastructure for the cell much like steel girders are used to create an infrastructure for a skyscraper. The proteins give the cell rigidity.

Stratum Corneum

Near the end of the differentiation process, the cell then moves into the stratum corneum, where the cell flattens into a disc-like shape, similar to a pancake. The stratum corneum is approximately 20 to 30 cell layers thick depending on location. Some areas are very thin, such as behind the ears, while other areas, such as the palm or the sole of the foot, are very thick.

The cells must remain flexible and still prevent the entry of environmental pollutants. The cells perform this miracle with a rigid hydrophilic structure composed of proteins, and a flexible hydrophobic structure composed of lipids. The cells of the stratum corneum must stick tightly together; yet, they must fall off individually when the right time has come for them to do so. Scientists have no idea what constitutes the "right time."

The average person replaces their entire epidermis approximately every 28 days. Cells are constantly falling off, but as long as the cells fall off individually, no one can see the cells. The average person loses about one million cells in bed each night. In addition, the average person loses about an ounce of cells every 24 hours. If the cells decide to stick together and fall off in clumps, we can see the process and call it peeling. This happens following a sunburn, after using a strong surfactant, or in some skin diseases.

Another change that occurs in the stratum corneum is that the pH of the skin cells decreases, becoming slightly more acidic. The subcutaneous layer, the dermis and the living layers of the epidermis maintain a pH of about 7.4 while the skin surface pH is about 4.5 to 5.5. As the cells move from the stratum granulosum to the outermost layer of the stratum corneum, the pH decreases or becomes more acidic by about two units. Thus, the acidic pH helps the stratum corneum to stick together and to maintain a good barrier against environmental insults.

Additionally, the stratum corneum reduces the penetration of ultraviolet radiation. Areas of thick skin, such as the sole and palm, rarely burn because the stratum corneum essentially blocks the penetration of ultraviolet light. Areas of thin stratum corneum do not have the same protection, so they require sunscreen. As the skin receives additional UV radiation, the stratum corneum thickens to block more radiation from reaching the living cells. As the layer thickens, the cells pack more melanin inside, so the skin darkens in response to UV radiation, becomes thicker and increases melanin production.

The next step to skincare is learning how environmental insults such as ultraviolet radiation, pollution and cleansers influence and change the skin's biochemistry and physiology. Combining this with basic skincare knowledge will help make you the skincare expert your clients deserve.