The New Age Spa Institute 1870 Busse Hwy, Des Plaines, IL 60016 847-759-0900 www.newagespainstitute.com Sensitive or Sensitized Skin SKIN PHYSIOLOGY The skin is made out of three major layers: Epidermis Dermis Subcutaneous Photo courtesy of Google Images Each layer plays an important role and it goes through many chemical reactions and physiological changes. Human skin is a beautiful yet very complex organ. Each layer undergoes through different stages in developing the top protective layer of our skin. The epidermis, the top most layer of skin, is only 0.1 to 1.5 millimeters thick. It is made up of five layers (starting from the deepest): • Stratum germinativum (basal) • Stratum spinosum (spiny) • Stratum granulosum (granular) • Stratum lucidum (clear) • Stratum corneum (horny) Working together, these layers continually rebuild the surface of the skin from within, maintaining the skin’s strength and protecting the internal organs of human’s body. 1 Basal Layer The process of cell regeneration begins in the basal layer of the epidermis. This layer comprises of small round cells called basal cells, which are considered the stem cells of the epidermis. Stem cells are biological cells that divide during process of cell mitosis and differentiate into specialized cells. Stem cells are self-renewing and producing new cells. The cells continually divide during the process of regeneration and push the older cells towards the top of the skin. This process is called Cell Turnover and it begins in the layer of stratum germinativum. The name germinativum refers to constant renewal or germination of new cells. There are various cells located within basal layer, but estheticians should have an understanding of at least two: • Melanocytes • Keratinocytes Melanocytes play important role within the skin. They are specialized cells in which biosynthesis of melanin takes place, simply – melanocytes produce enzyme called melanosome, which in turn produces melanin (pigment). DNA predetermines the natural color of the skin: the higher the activity of melanosome, the darker the skin tone. The same understanding of melanocytes comes to play on daily basis. When our skin is exposed to sun – melanocytes start producing pigment. The idea is to produce a tan and prevent the skin from sunburn. Sunburn leads to internal inflammation of the skin; trauma caused to cells, which causes cell damage, permanent dilation of capillary walls, weakening of connective tissue, and severe dehydration leading to sensitivities. Not to mention hyperpigmentation! The activity of melanocytes within our skin allows for either nice, even tan OR creates almost immediate burning of the skin. The Fitzpatrick Type 1 burns almost immediately, versus Fitzpatrick Type 5 or 6 can be exposed to sun for longer period of time without visible damage. Freckles, age spots, melasma or white discoloration on the skin are all associated with melanocytes. Basal layer also contains other cells that play predominant role in the formation of the top layer of the skin: keratinocytes. Those cells undergo a transformation during the process of keratinization and turn into keratin (skin is made out of soft keratin). Corneocytes present in the top layer of the epidermis give the skin protection and prevent invaders from damaging the lower layers. Basal layer also contains Merkel cells, which are thought to be responsible for sensation via touch receptors. Langerhans cells are present in the basal layer and are directly responsible for the production of T-cells (immunity of the body). Basal layer contains live cells and is one (1) cellular layer in thickness. Spiny Layer This layer is located right above the basal layer. It is also known as stratum spinosum, because the cells are being held together with tiny spiny projections. In this layer cells have migrated from the basal layer and are changing in shape and maturity. Keratinocytes have begun production of keratin, a tough, protective protein that makes up a large part of the structure of the skin, hair, and nails. Cells from this layer are pushed upwards to stratum granulosum where once again they are undergoing changes. Spiny layer is the thickest layer of the epidermis and contains live cells that are at the end of their living cycle. Granular Layer Within the layer of stratum granulosum a process known as keratinization takes place, during which squamous cells undergo a change of becoming harder and stronger and are turning into soft keratin. This layer is impermeable to penetration of anything, except for the substances of the tiniest molecular size, which give this layer a name of “waterproof layer” of the skin. The waterproof component is due to special lamellar granules that are present within the granular cells and those secrete sheets of fatty substances. Those fatty substances are deposited into the spaces between 2 the cells of stratum granulosum, forming a waterproof sealant. The main job of this sealant is to protect the lower layers of epidermis by not allowing penetration from the outside invaders. Clear Layer The layer of stratum lucidum is named for its translucent appearance under a microscope. It is a thin, clear layer of dead cells of specialized keratin, known as eleidin. This intermediate form of keratin is made of very small granules. Stratum lucidum is only found in the areas of thick skin, mostly noticeable on the palms of the hands and soles of the feet. Horny Layer In this layer of the skin cells complete their migration. During the process of cell turnover cells change shapes, flatten, bond together, then eventually become dehydrated and die. Stratum corneum is made up of over 95% of dead cells held together by intercellular cement. Increased external pressure or friction can cause thickened areas in the stratum corneum known as corns or calluses. In the average adult, it takes nearly a month for the stratum corneum to be completely replaced. This process is known as natural desquamation (exfoliation) of the skin. The replacement process (cell turnover process) generally slows with age. The top layer of epidermis is protected by hydrolipidic film (HLF) a combination of lipids, sweat and dead cells that has an important job of providing an invisible, protective layer on the skin. Dermis This layer also referred to as True Skin is located under the epidermis. Over 70% of the dermis is comprised of collagen and elastin tissue (connective tissue) that provides structural support to the skin. Collagen is responsible for holding hydration in versus elastin corresponds to elasticity of our skin. Capillaries, sensory nerves, sebaceous glands, sudoriferous glands, lymph, arrector pili muscle, hair follicles, GAGs and other substances are housed in the dermis. Healthy dermis provides stable support and nourishment through capillary diffusion to epidermal layer of the skin. Subcutaneous This layer of adipose tissue is located under the dermis and separates the skin from underlying organs. It acts as a cushion, and gives our skin nice contour. As we age this layer shrinks, especially on the face. As estheticians we are directly working with the Stratum Corneum (outermost of the epidermis), but it is imperative to know and understand all layers of the skin. Sensitive skin A skin type or condition? Up to 90% of the population perceives their skin as sensitive. But do they really have sensitive skin? Sensitive skin affects millions of people, but the exact definition varies depending on whom you ask. We are all born with a skin type that has been assigned to us as a biological makeup of our bodies during the time of conception. And yes, it’s true - we are all born with the same size pores on our faces. If we were to compare two newborns together, we would notice that the sizes of their pores are the same. They will continue to be the same for several years, until the time they hit puberty. At this time our bodies undergo many hormonal changes, and this is when the sebaceous glands (regulated by the Androgen hormone) start producing more or less sebum. This change in hormones will be directly related to teenage acne for some teenagers, while others will only experience an occasional breakout. During puberty we also start to notice the changes in the oil production of the skin. For those with higher production the pores stretch, become filled with excess sebum, and their skin starts showing the characteristics of an oily skin type. For those whose bodies are not producing 3 enough sebum the pores are going to stay small, filling up with sebum in few areas of the face only (such as chin, nose etc.). There will also be those individuals in between. Commonly known skin types: • Oily • Combination Oily • Combination Dry • Dry Yet there are some individuals that claim to have sensitive skin as a type. Can this be possible? It’s up to the esthetician to understand the difference in what may be the cause of this sensitivity. Is this skin truly sensitive or is it sensitized? A true sensitive skin condition is caused by a genetic predisposition. Someone who is truly sensitive is born with this condition and tends to be prone to blushing, asthma, and allergies. This skin is considered more delicate with a lower amount of pigment, a thin epidermis, and blood vessels close to the skin surface, hence the occasional appearance of redness. This genetic predisposition is found in those who have very fair skin and are usually of Northern European ancestry. This genetically pre-disposed sensitivity of the skin has nothing to do with oil production and it can affect anyone with oily or dry skin types. The skin of someone who is genetically sensitive may appear without any visible outside irritations, but will react quickly to touch, product or to both.