The Anatomy Of The Skin

Compared to the evolution of the sun, the concept of tanning indoors is fairly young and we continually are discovering new ideas, concepts and facts that were previously unknown. A salon owner or operator needs knowledge of how to run a successful business as well as an understanding of the biology of the skin and the process of tanning.

The skin is body’s largest organ. The skin of an average adult weighs eight to 10 pounds and has an average area of about 22 square feet. The skin’s purpose is to protect the body against injury, infection, heat, cold, and store water, fat and vitamins. The human skin is rejuvenated about once every four weeks.

Thinking of the skin as an organ, rather than something that can be used and abused, puts things in proper perspective. The skin is a wonderfully resilient organ and, for the most part, can survive virtually any form of punishment. The skin is the body’s boundary, tough enough to resist all sorts of environmental assaults, yet sensitive enough to feel a breeze.

A versatile organ, skin creates the first line of defense against possible invasion by bacteria and germs, while maintaining the body’s internal environment to within a few degrees of normal throughout our lifetimes. The skin also secretes fluids that lubricate it and barricade toxic substances, while maintaining this environment. The skin can absorb some soluble substances 

Melanin And Tanning 

It is the production of melanin that results in the golden look a tanner desires. Without melanin, the skin would burn when exposed to ultraviolet light. Fortunately, melanin gives a cosmetically pleasing appearance to the skin. The process is rather intricate. First, let’s take a look at the basic structure of the skin. (1) The hypodermis (subcutis) stores fat droplets and serves as a shock-absorbing cushion. (2) The corium (true skin) consists of resilient connective tissue and acts as a “girdle” supporting the body. The outer part of the corium contains blood vessels and nerve endings. (3) The germinative layer is one of two layers within the epidermis (cuticle). (4) The horny layer is the uppermost layer of the epidermis.

The skin comes equipped with special cells called melanocytes. When these cells are stimulated by ultraviolet light, they utilize an amino acid called tyrosine to produce the pigment melanin. The cells can store small amounts of tyrosine. The melanin pigment is only able to absorb ultraviolet light of approximately 320 nm, therefore, UVB rays are needed to achieve melanin production. UVA can formulate melanin, but only when there is enough photosensitizing material already in the skin to trigger a UVB reaction. Melanin is defined as a dark pigment found in the retina, hair and skin, except for the palms of the hands, soles of the feet and lips.

Melanin granules are pink in color and are formed in the melanocytes, the production cells for new pigment grains. Pigment travels upward toward the horny layer of the epidermis where it is stored around the nuclei of keratin cells. Keratin is a strong, fibrous protein that is the basic substance of nails, hair and the horns and hoofs of animals. These cells are forced outward during the tanning process and harden on the surface where they eventually disappear through flaking.

Because of this process, we are constantly developing new skin every four to eight weeks. In this way then, the pigment protects the UVB-sensitive DNA located inside the cell nuclei without obstructing the other positive effects of ultraviolet light, such as vitamin D synthesis. Energy absorbed by pigment granules is returned to the cell in the form of heat. In the beginning stages of melanin production, the skin has very little protection. This is why the importance of slow tanning is emphasized. UVA penetrates deeper than UVB, causing damage to the corium. Damage to this layer of the epidermis hastens aging and destruction of collagen and connective tissue. A UVA burn can be much more damaging because it is not felt due to its deep penetration. This is why moderate tanning is a must.

Overexposure may cause acanthosis, or thickening of the horny layer, which can give a person a dull look. Clients of indoor tanning salons should receive a dose that neither overexposes nor underexposes them to UVR. No one should be allowed to tan for longer than the approved MTI (maximum timer interval) of the tanning unit.

In order for the pigmentation process to be effective, melanin granules must be oxidized or darkened, which requires a high dose of long-wave UVA. A sufficient amount of energy must be provided to initiate the oxidation process. UVB causes quickening of the migration of germ cells to form a thicker horny layer. In short, UVB synthesizes pigment granules, while UVA only ensures their oxidation. Together, the two form a light-protection mechanism.

Please note that a tan produced by UVA light alone only gives the illusion of light protection because the skin appears to be more tanned. Actually, neither a thickening of the skin nor pigmentation has taken place, which means the skin is as vulnerable to ultraviolet light as before.

Melanin is the leading factor that determines a person’s skin color, and its presence is determined by hereditary factors. This is based on the regions of the world from which a person’s ancestors came and is referred to as constitutional skin color. But not all skin color is based on constitutional skin color. Facultative skin color, referred to as tanning, is the result of deliberate exposure to ultraviolet radiation. Here, hormonal factors determine the shade of a tan one will develop.

Each skin type reacts in its own way to UV radiation. The reaction is dependent upon the amount of pigment already in the skin naturally, the capability to build up additional protection (facultative pigmentation) and the degree of thickening of the uppermost horny skin layer (acanthosis).

All of these factors are determined genetically. In the initial stage of tanning, the skin has what are called pre-pigment grains that appear gray-brown in color. The visible result of these grains is immediate tanning, seen in people who tan easily. However, this color can disappear very quickly, in as few as 24 hours. In the lowest layer of the outer skin, the melanocytes (melanin-producing cells) begin to generate new pigment grains called melanosomes. Because this is a slower process than the immediate tanning of pre-pigment grains, it is known as indirect pigmentation. With the presence of UVB, melanocytes are stimulated to divide, creating more pigment cells. During this time, the epidermis thickens to form additional protection, again a condition referred to as acanthosis.

The actual production of melanin occurs deep within the outer skin where melanocytes are situated. Melanocytes are capable of growing between the surrounding keratinocyte cells and forming offshoots called dendrites. It is at this point that melanocytes have the ability to be stimulated by UV rays to achieve their purpose of producing melanin. Eventually, the pigment grains change from their initial pink color to their final stage of reddish-brown or a tan. The peak color that can be achieved is dependent upon an individual’s tanning schedule and individual factors such as skin type, hormonal influences and recent UV history.

Melanin can compensate for only so much UV light. It’s not difficult to spot a tanner who has had too much UV exposure. Photo-induced inflammation, better know as a sunburn, is the result of an overdose of UVB rays. Longer wave UVA produces a reddening of the skin only when sufficient photosensitizing effects are taking place, due to an excess dosage or a high concentration of photosensitizing substances, such as certain medications, perfumes or lotions. A sunburn resulting from too much UVB causes cell damage on only the top germinative layer where cells eventually flake off. A sunburn from UVA, however, reaches deep into the connective tissues, permanently damaging the delicate elastic fibers of the skin.

Clients need to be educated on the tanning process and made aware that it takes some time. It takes six to 10 sessions—following the exposure schedule—for a previously unexposed individual to develop a base tan.

The tanning process occurs in two phases. The color seen immediately after getting out of a tanning unit is due to immediate pigment darkening (IPD). IPD results from the rapid darkening of already existing melanin and is induced mainly by UVA. It is most obvious in skin where high levels of pigmentation already exist. IPD can fade within minutes or last up to several days after longer exposures and blend into the delayed tanning phase.

The delayed tanning phase first becomes visible 72 hours after exposure. It is induced mainly by UVB and is the result of increased melanin. By creating an excited condition in the melanocytes which then release more melanin, both UVA and UVB contribute to the delayed tanning phase.

Because the length of IPD is primarily determined by skin type, certain individuals will experience IPD for only a few minutes. It is important to educate these clients on the tanning process, otherwise they may incorrectly perceive that they did not receive adequate color from their tanning session and try to tan again within a 24-hour period. This could lead to unintentional overexposure. Supplementing sunless-tanning options along with UV tanning will allow these clients to have immediate color while they develop their base tans.