Your Skin

The skin is an organ that forms a protective barrier against germs (and other organisms) and keeps the inside of your body inside your body, and keeps what's outside of your body outside. Skin is comprised of about 70% water, 25% protein, and 2% lipids. 

Skin also helps maintain a constant body temperature, and it is only about 0.07 inches thick.  On average, an adult has from 18-20 square feet of skin, which weighs about 6 pounds.

Skin is made up of two layers covering a third fatty layer. The outer layer, the epidermis, is a tough protective layer that contains melanin (which protects against the rays of the sun and gives the skin its color). The second layer (located under the epidermis) is called the dermis; it contains nerve endings, sweat glands, oil glands, and hair follicles. Under these two skin layers is a fatty layer of subcutaneous tissue.

The epidermis, as noted above, is the outermost layer.  It renews itself every 3 to 5 weeks. The epidermis is not very thick, only 0.097 to 0.0394 inches. It is thickest on the palms and thinnest on the eyelids.

The epidermis consists of 3 types of cells: keratinocytes, which are predominant; melanocytes, which produce the melanin responsible for skin color and tone; and the langerhans cells, which work to prevent unwanted substances from entering the skin.

The epidermis also contains 5 layers. From bottom to top the layers are named stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum. The bottom layer, the stratum basale, has cells that are shaped like columns. In this layer the cells divide and push already formed cells into higher layers. As the cells move into the higher layers, they flatten and eventually die. The top layer of the epidermis, the stratum corneum, is made of dead, flat skin cells that shed about every 2 weeks.

The layer under the epidermis is the dermis, which is the middle layer. This layer is the thickest. The dermis itself has two layers: the upper, or papillary, and the lower, or reticular. The papillary layer contains a thin arrangement of collagen fibers, and the lower layer is made up of thick collagen fibers arranged parallel to the skin’s surface.

The dermis is comprised of three types of tissue that are present throughout, not in layers: collagen, elastic tissue, and reticular fibers.  In addition, the dermis contains capillaries, which are blood vessels; lymph nodes, which are responsible for collecting and destroying bacteria that have entered the body; sebaceous, or oil, glands; hair follicles; and some nerve and muscle cells.

The hair follicles are also located in the dermis, with the erector pili muscle that attaches to each follicle; and apocrine (scent) glands are associated with the follicle. This layer also contains eccrine (sweat) glands, but they are not associated with hair follicles. Blood vessels and nerves, which transmit sensations of pain, itch, and temperature, course through this layer. The dermis also contains specialized nerve cells called Meissner's and Vater-Pacini corpuscles that transmit the sensations of touch and pressure.

The key cell in the dermis is the fibroblast.  This cell synthesizes collagen, a fibrous protein found in connective tissue; elastin, the basic constituent of elastic connective tissue; and other molecules responsible for the skin’s structure.

The innermost layer of the skin consists mostly of fat and connective tissue and is called subcutaneous tissue. This layer houses larger blood vessels and nerves, and is important in regulating the temperature of the skin itself and the body. The size of this layer varies throughout the body and from person to person. Directly below the subcutis (epidermis and the dermis) is usually a layer of muscle or bone.

Anatomy of Hair

There are two general types of hair – terminal hair and vellus hair.

Terminal hair grows thick and long, and is what grows on the head, axilla and pubic area, as well as on the face, chest, arms and legs.Terminal hairs are the type of hairs that are removed by the laser.

Vellus hair is a very soft, short hair that grows most places on the body in both sexes. In Caucasians it’s often colorless, or blonde. It is best seen in women and children, as they have less terminal hair to obscure it.

A third type of hair, lanugo hair, is present in the fetus, and some newborn babies.  It can  also be seen on the bodies of those who are extremely emaciated.

Human hair grows only six inches per year, and grows faster in the summer than in the winter.  Hair has three growths stages: anagen, catagen, and telogen. Hair goes from anagen, which is the active growth phase, to catagen, the phase where hair transitions to its resting phase, and then to the resting phase, which is the telogen phase.

Anagen is the active phase. This is the phase where hair does its actual growing. In fact, it is in this phase where 84 percent of growth occurs. In the active, or anagen phase, hair grows about .39 inches every 28 days. Scalp hair is in this active phase for 3 to 6 years before it moves to the transition, or catagen phase. The hair on our arms and legs, and our eyelash and eyebrow hair, have a very short active phase of only 30 to 45 days.

The next phase, the transitional or catagen phase, lasts 1 to 2 weeks. It is in this phase that the follicle stops producing hair.  Only 1 to 2 percent of our scalp hairs are in the transitional, or catagen phase at any one time. It is also during this phase that no pigment, or coloration, is made.

The final phase is the telogen, or resting, phase. Ten to fifteen percent of our hairs are in the telogen phase at any one time. This phase lasts about 100 days for the hair on our scalp, and longer for our eyebrow and eyelash hair, arms and legs. The hairs that we notice left on our hairbrush or in the sink when we shampoo are the hairs in this phase; they come out because they’re making way for the new hairs, which will be produced during the anagen, or growth, phase.

The hair essentially has three regions: lower, middle, and upper, and two sheaths: inner and outer. The sheaths protect the hair, and mold the growing hair shaft, which accounts for the shape hair takes (curly, straight, or wavy, for instance).

Hair has a follicle, which we don’t see because it’s embedded in the skin; and a shaft, which is the portion visible to us. The lower segment of the hair, which extends from the base of the follicle to the insertion of the erector pili muscle, consists of two parts: the bulb and suprabulb.

The bulb is the bottom part of the hair closest to the scalp and is the only living part of the hair. That means that the part of the hair visible to us is actually dead! The bulb surrounds the papilla and is the only part of the hair fed by capillaries. In the bulb, cells divide every 23 to 72 hours, which is faster than other cells in the body.

The middle segment of the hair is called the isthmus. This is the short section that extends from the insertion of the erector pili muscle to the entrance of the sebaceous gland duct, commonly known as a “sweat” or oil gland.  A muscle, called an erector pili muscle, attaches below the gland to a fibrous layer around the outer sheath. When this muscle contracts, it causes the hair to stand up and is responsible for “Goosebumps”.

The upper segment of the shaft extends from the entrance of the sebaceous, or sweat, gland duct to the follicular orifice, ( the place where the follicle extends from its opening).

The sheaths both protect the hair and mold the shaft to help determine the hair’s shape.

The inner root sheath, which we’ll call “IRS”, follows the hair shaft.  The IRS has no pigment, or color. Its function is to coat and support the hair shaft up to the level of the isthmus (or the middle segment).

The IRS ends below the opening of the sebaceous gland and sometimes the apocrine (scent) gland.

The ORS, or the Outer Root Sheath, covers the IRS, or inner root sheath.  The ORS extends upward from the matrix cells at the lower end of the bulb to the entrance of the sebaceous gland.   It is thinnest at the level of the bulb and thickest in the middle portion of the hair follicle.  The "bulge" region in the ORS is the site at which the erector pili muscle is attached.

Now, about the three of the hair shaft. The outermost layer, the layer that we see, is called the cuticle.  It consists of overlapping cells arranged like shingles. It is thin and colorless, and its job is to protect the thicker cortex that contains the melanin.  These shingles point outward and upward, and interlock with the IRS (inner root shaft) cuticle, leading to the firm attachment between the hair shaft and the IRS. The cuticle moves upward in the follicular canal as a single unit.

The middle layer, or the cortex, makes up the bulk of our hair. Our hair is made up of keratin, a tough, fibrous, insoluble protein forming hair and finger nails. “Keratinized” hair is fully hardened, and it is in the cortex where hair begins this keratinization process.

It is also in the cortex where melanin is present.  Melanin is responsible for hair color, but the actual color depends on the kind of melanin present. The two types of melanin are eumelanin, which creates brown or black hair, and pheomelanin, which makes hair appear red. Blonde hair results from very low amounts of melanin, and gray hair results from a lack of melanin, often caused by age but can also be caused by stress and illness.

The medulla is the innermost layer of the hair, and is the layer that is difficult to see. The medulla is composed of cells that are not very adhesive and are often pigmented, with larger granules than those in the cortex, separated by air pockets.  The medulla reflects light, giving hair its various color tones. That is why hair color looks different in sunlight than in shade. 

As mentioned, the two forms of melanin are eumelanin, which makes up brown and black hair, and pheomelanin, which makes up red and blonde hair. Melanin (color) granules are spread throughout the cortex, and melanin is formed in the pigment-producing cells in the hair bulb during the growth, or anagen phase.

Skin Type

To make sure you are a good candidate for any of the procedures we offer, several steps must be taken before treatment can begin.  These steps are done by the Aesthetician and center staff with your input. 

One of the most important factors is skin typing.  We must make sure that we correctly type your skin to give you the safest, most effective treatment.  To do this, you will answer some questions about your genetic background, reaction to sun exposure, and tanning habits. 

Skin type is categorized according to the Fitzpatrick Skin Type Scale.  Classification depends on the amount of melanin pigment in the skin.  A picture example is found below, and typical features of each skin type are listed in the chart below:

Skin Type	Skin Color	How the skin reacts to sun
I	Very fair, "transparent"	Always burns, never tans
II	Fair	Always burns, tans with difficulty
III	Fair to light olive	Burns mildly, tans slowly
IV	Olive to brown	Rarely burns, tans with ease
V	Dark Brown	Very rarely burns, tans very easily
VI	Black	Never burns, tans very easily

We may also ask you for a spot test before we perform a treatment.  This is for safety and reassurance to you if there are any areas of concern.  The spot test is used to test the skin’s reaction to the laser.  

We will also ask you about recent sun exposure.  If you’ve been in the sun recently, we may have to adjust setting on the laser to ensure your safety.