Technical Terms

Acid - A water-soluble agent able to produce positively charged hydrogen ions (H+). Compounds that have a sour taste, turn litmus paper red, and react with a base to form a salt. On the pH scale from zero to 14, an acid ranks 0–7. Healthy skin is slightly acidic, pH between 5.5 and 6.5. (See Base, Alkaline, and pH Scale.)

Acid Reactivity - The potential of an acid to chemically react with other substances resulting in an energy release.

Acne - A multi-factorial inflammatory skin disorder, often the result of hormones acting on the skin's oil (sebaceous) glands causing clogged pores and breakouts. Oil from the glands and dead skin cells block the hair follicles, leading to bacteria buildup beneath the blocked pore. This causes visible inflammation in the form of pimples, whiteheads, or blackheads. The most common form of acne is known as Acne vulgaris, which means "common acne." (See Blackhead, Comedone, and Whitehead.)

Activate - See Activation.

Activation - In biology, to stimulate a cell in its resting state to become active.

Activation Phase - The initial phase of skin pigmentation. In this phase, UV light and other aggressors stimulate the body to release irritation, stress, or hormone initiators that bind receptor sides on the melanocyte, telling it to begin melanin production. (See Expression Phase, MSH, Keratinocytes, and Synthesis Phase.)

Active Ingredient - The ingredient agent primarily responsible for the intended benefit of a product. In some FDA regulated products like sunscreens, the active ingredient, sunscreen agent, and protection level will be listed on the package.

Aesthetic - A term relating to standards of beauty and art. Associated with the senses of touch, sight, and smell. Often applied to cosmetic formula design or end product and how it feels, smells, dries/rubs in, and enhances the skin or hair.

Aesthetician - A licensed professional who recommends and practices cosmetic skin care treatments for health and beauty. Trained in a variety of techniques such as microdermabrasion, chemical peels, facials, manicures, and pedicures.

Affinity - A natural attraction to something. In chemistry, it is the tendency of one molecule to associate with another or the measure of intrinsic binding strength of one compound to another. Affinity is a tolerance of distance. A great affinity would be a tolerance or liking of close proximity. A lack of affinity would be an intolerance or dislike of close proximity.

Age Spots - Small, flat, pigmented spots most often seen on areas of the body that have been exposed to the sun over a period of years. Age spots usually occur after the age of 40. These brown spots found on the skin are visible evidence of accumulated long-term sun damage, known to dermatologists as "lentigines." Also called "liver spots."

Agent - A substance or ingredient that exerts a specific effect or result.

Airborne Particles - Dust or minute droplets of liquid small enough to remain suspended in the air. Often too small to be seen by the naked eye, they can be inhaled.

Alcohol - The family name for a group of organic chemical compounds that contain one or more hydroxyl groups (OH). Alcohol has a wide range of forms and uses in cosmetics: some are humectants, others like fatty alcohols are emollients or cleansing agents. However, some small chain alcohol molecules like ethanol, methanol, or isopropyl—can be drying and irritating to skin or hair.

Alcohol-Free - A product without a small chain alcohol like ethanol, which tends to dry out skin and hair.

Algae - Primitive, chiefly aquatic, one-celled or multicellular plants that lack true stems, roots, and leaves but usually contain chlorophyll. Included among the algae are kelps and other seaweeds, and diatoms. Also known as phytoplankton. Used in skin care products as conditioning, water binding, and antioxidant agents.

Alkaline - Refers to a substance with a high pH having properties of a base. (See Base.) On the pH scale from 0 to14, a base ranks 7–14. Any pH over 7 is considered alkaline. Skin irritation could be caused by products with high alkalinity, pH 8 or higher. (Also see Acid and pH Scale).

Allergen - A substance that can produce a hypersensitive reaction or trigger an allergic response in the body. An allergen can cause a reaction if eaten, touched, or inhaled. An adverse reaction could manifest in sneezing, coughing, rash or irritation.

Alpha Hydroxy Acid (AHA) - Group of water soluble acids that appear naturally in fruit. They are weak hygroscopic acids that absorb atmospheric moisture. On the skin, they accelerate exfoliation, cell renewal, tone, even out pigment, and hydrate.

Amino Acid - An organic compound that is a basic structural unit of peptides and proteins. Aspartic acid, glutamine, glycine, lysine, tryptophan, and tyrosine are amino acids. Used in skin care products as water-binding agents, pre-cursors, antioxidants, and up-regulators.

Anti-Androgen - Any substance that inhibits production of androgens (male sex hormones). Anti-androgens usually work by blocking the appropriate receptors, competing for binding sites on the cell's surface, obstructing the androgens' pathway.

Antibacterial - Hostile to bacteria and germs, therefore able to fight infection. Also known as bactericides. This terms differs from bacteriostatic, which refers to substances that keep bacteria from growing, but may not destroy them.

Antimicrobial - An agent which destroys or inhibits microbial growth.

Antioxidants - Agents that inhibit or neutralize potentially harmful compounds known as free radicals. Antioxidants are substances that protect cells from oxidation by absorbing or scavenging the free radicals. Well-known antioxidants include, vitamins C and E, beta-carotene, and CoQ10. When topically applied, antioxidants help prevent skin aging by protecting cellular components like collagen and elastin. (See Free Radicals.)

Apocrine Glands - Specialized sweat glands that secrete an odorous substance. Found under the arms and in the groin area; they secrete a milky white substance and are responsible for body odor.

Arid - Extremely dry and lacking moisture.

Aroma - A distinctive scent, usually from plants or herbs in aromatherapy.

Aromatherapeutic - The quality of being treated through aromatherapy. (See Aromatherapy.)

Aromatherapy - The treatment of the skin and body through natural oils and aromas. Treatments include massage, steam, or inhalation of certain herbs.

Aromatic - In aromatherapy, having an agreeable odor or stimulating quality.

Atrophy - The wasting away of tissues, organs, or cells in the body.

Autosomal - Any chromosome other than sex chromosomes X, Y. In humans, there are 22 pairs of autosomes.

Bacteria - One-celled living organisms, typically about one micron in diameter. They are among the oldest, simplest, and smallest types of cells. Some cause infections and disease in animals and humans and are a key element in organic decomposition.

Balm - An ointment designed to soothe and heal.

Barrier Function - Refers to the role the skin plays in protecting the body from infection and water loss. The protein-lipid molecular structure of the epidermis is crucial to the maintenance of this important barrier. (See Ceramides, Cholesterol Esters, and TEWL.)

Basal Layer - Deepest or lowest layer of skin epidermis; it borders the dermis and other epidermal layers. This layer is only cell deep and connects the epidermis with the rest of the body. Here keratinocytes (skin cells) proliferate and melanocytes produce melanin or skin pigment. (See Epidermis, Keratinocytes, and Stratum Corneum.)

Base - An water-soluble agent able to produce negatively charged hydroxide ions (OH-). Base turns litmus paper blue and reacts with a acid to form a salt. (Also see acid, alkaline, and pH scale.) In cosmetics, base can mean foundation or skin-colored makeup that is used to smooth skin surface and even tones. Cosmetic bases come in liquid, cream, powder, cake, and stick product forms.

Base Note - In fragrances, base note refers to the final expression of the fragrance after it has dried on the skin (after 20 minutes) and reveals how the fragrance will smell as the consumer wears it. Also known as the "end note." (See Mid Note)

Beta Hydroxy Acid (BHA) - An oil-soluble exfoliant derived from fruit and milk sugars used in skin care to treat wrinkles, blackheads, and photoaging. Salicylic acid is an example of a beta-hydroxy acid. While alpha hydroxy acids are water soluble, beta hydroxy acids are lipid (oil) soluble and better able to penetrate, exfoliate, and unblock pores. Also, helps renew aging skin. (See Alpha Hydroxy Acid.)

Biological Aging - The process of getting older due to natural biological changes that happen with the passage of time and genetics. Also known as intrinsic aging. (Also see Chronological Aging.)

Bio-Mechanisms - Cellular process and functions such as thermogenesis, fat storage reduction, and stress management that keep the body running at an optimal level.

Biosynthesis Pathway - The production by living organisms of complex substances from simple reagents. Unlike chemical synthesis, it takes place within living organisms and is generally catalyzed by enzymes, consumes energy, and is vital part of metabolism. Important biosynthesis products include proteins, vitamins, and antibiotics.

Birthmark - A mole or blemish on the skin that is present from birth.

Blackhead - A non-inflammatory acne lesion that is filled with excess oil and dead skin cells. Also called an “open comedome” because the hair follicle or pore remains open. Blackheads form when skin pores get clogged with oils/impurities and become dark by oxidation or contact with air. Blackheads differ from whiteheads because the follicle remains open, where as whiteheads are covered with a layer of skin and are more likely to become infected. Deep cleansing of the skin can help prevent blackheads. (Also see Acne, Comedone, and Whitehead.)

Bleaching - In oral care, a technique that lightens the color of heavily stained teeth.

Body Odor - Condition or smell caused by body perspiration and bacteria living on the skin--most commonly under the arms or other moist places where bacteria can proliferate.

Botanical - Refers to substances derived from plants or plant parts. A plant-based product.

Brightness - The perceived intensity of a radiating object. In skin care, this term describes luminous skin tone free from discoloration and dark patches.

Broad Spectrum Protection - In sun protection products this refers to a sunscreen with both Ultra Violet A (UVA) and Ultra Violet B (UVB) rays.

Canfield Studio Camera System - A high resolution digital camera system used under controlled studio lighting to visibly document performance (before and after shots) of Nu Skin® products.

Carotenoids - Natural, oil soluble pigments ranging in color from yellow to red (includes carotenes and xanthophylls). There are more than 600 known natural carotenoids, all of them synthesized only in plants. Lycopene, phytoene, phytofluene and beta-carotene belong to this family. Carotenoids are antioxidants. When plants are exposed to sunlight the carotenoids absorb light, capture the energy, neutralize the free radicals and protect the plant. Nu Skin's patented "colorless carotenoids" is a cosmetic ingredient activated by UV light, used to protect the skin.

Catechins - Bioflavonoids and powerful antioxidants with a polyphenolic structure (present in green tea, grapes, wine, and chocolate). Due to their potent antioxidant capabilities, catechins (or "tea flavonoids") are being studied for their protective effects against cancer and heart disease.

Cavity - In oral care, a cavity is a hole in the tooth due to decalcification of the enamel and disintegration of the dentin by acid-producing bacteria. Progressive decay can lead to the death of a tooth.

Center for Disease Control (CDC) - A federal agency that provides health and safety information to control disease, improve environmental health, and promote health education activities.

Cell Membrane - The outer boundary of the cell. It is a permeable envelope comprised of phospholipid bilayer that regulates the flow of material into and out of the cell. Also called plasma membrane.

Cell Proliferation - An increase in the number of cells as a result of cell growth and cell division. It could occur when a tissue abnormality is present like a tumor.

Cell Renewal - The continuous process of new cells being created to replace dead cells. Skin cells are constantly shedding and being renewed. As new skin cells are produced at the basal layer of the epidermis, they push up older cells. As these skin cells, or keratinocytes, migrate to the skin's surface, they flatten and harden. The outermost skin cells slough off as younger cells rise through the layers below. The rate of cell renewal slows as we age.

Cellular Durability - The ability of cells to reinforce the skin's defense mechanisms and protection.

Cellular Energy - Term used to describe a cell's capacity to do work. Cells derive energy by breaking down glucose and capturing the released energy in the form of high energy bonds in molecules such as ATP.

Cellular Oxidation - Reaction of a cell with oxygen, usually resulting in degradation. The process of oxidizing is the addition of oxygen with a loss of electrons; always accompanied by reduction. Cellular oxidation by free radicals contributes to skin aging.

Cellular Repair - Process by which the cell restores, reconstructs, or renews parts for the purpose of maintenance. For example, proteins are used and new ones are constantly being synthesized. Lipids and carbohydrates are also continuously being recycled into simpler components.

Cellular Respiration - The metabolic process in which a cell obtains energy breaks through a series of biochemical steps typically involving the consumption of oxygen and liberation of carbon dioxide and water. Cellular respiration may be anaerobic or aerobic, depending on the availability of oxygen. Also referred to as cellular metabolism.

Cellulite - A cosmetic defect caused by the breakdown or thinning of connective structure beneath the surface of the skin in the upper compartment systems of fat tissue making fatty deposits that cause a dimpled or uneven appearance of the skin, usually around the thighs and buttocks.

Ceramides - Naturally occurring skin lipids (fats) that act as intercellular mortar. They make up the bulk of the lipid layer which holds the skin's cells together in a firm, smooth structure and help protect the skin from water loss by forming a protective barrier. Ceramides naturally decline with age resulting in dry, less flexible skin. (See Barrier Function.)

Chafing - Causing something to be sore from rubbing or shaving.

Chelate - Also called sequester, it is the process of preventing metals in the water from combining with other components.

Chemical Exfoliation - The process of removing the top layers of dead skin cells using chemical agents. Exfoliation encourages skin renewal by smoothing wrinkles and evening texture.

Chemical Reaction - A change or interaction between substances resulting in a new substance. Usually involves the making or breaking of chemical bonds.

Chemically Treated Hair - Term generally used to describe hair that has been bleached, colored, or permed.

Cholesterol - A fat-like substance produced in the body and found in certain foods. Important part in cellular health and a necessary component of all cell membranes.

Cholesterol Esters - Created from cholesterol and an organic acid, these large fatty acids are ideal for transporting and storing water. In skin, they help maintain moisture and enhance barrier function. (See Barrier Function.)

Chronological Aging - The process of getting older due to natural biological changes that happen with the passage of time and genetics. Also known as intrinsic aging. (See also Biological, Environmental, and Mechanical Aging.)

Clay - A generic term for firm, finely ground earth that often contains minerals. It is plastic when moist and usually hardens as it dries. Used in cosmetics for exfoliation, conditioning, and removal of impurities from skin.

Clinical Grading - Classification or standard established for the evaluation of a test or clinical study. May involve analytical instrumentation and subjective determination by professional clinicians. (See Clinical Study.)

Clinical Study - An organized procedure in an controlled environment for determining the safety, efficacy, and effectiveness of a material. Usually involves consenting human subjects. (See Cinical Grading.)

Clinically Proven - In cosmetics, the term refers to product claims and benefits that were validated by a clinical study. (See Clinical Study and Clinical Grading.)

Collagen - The main structural protein of skin, bones, tendons, cartilage, and connective tissue. A tough fibrous protein with great tensile strength. Has the ability to resist the forces of stretching and maintains the structural skin integrity. Collagen degradation associated with age, exposure to sunlight and pollutants results in lines and wrinkles.

Collagenase - A type of enzyme (proteolytic) that breaks down the collagen protein. It acts as a catalyst to hydrolyze the collagen (add water and break protein bonds).

Comedone - Commonly known as blackheads or whiteheads. Hair follicle becomes plugged with sebum. When the lipid or sebum is exposed to the environment it is oxidized and turns black (blackheads). When the follicle is closed and not exposed to the environment it is cream colored. (See Acne, Blackhead, and Whitehead.).

Complexion - The overall natural texture and appearance of the skin of the face.

Compound - Consisting of two or more substances, ingredients, elements, or parts. In chemistry, a substance formed by chemical union of two or more elements.

Constrict - In biology, term used to describe the tightening or narrowing of blood vessels that compress or slow blood flow.

Corneocytes - Dead cells of the stratum corneum which contain keratinized horny material. Good at providing an external environmental barrier and preventing water loss. (See Epidermis, Keratinocytes, and Stratum Corneum.)

Corrosive - A substance that eats or wears away materials gradually. Capable of slowly dissolving especially by chemical action.

Crow's Feet - Term used to describe fine lines and wrinkles that appear at the outer corner of the eyes, sometimes referred to as laugh lines.

Cumulative - Effects of repeated exposures. In cosmetics, increasing benefits by successive addition or application of product.

Cyst - A sac that contains semisolid or liquid contents. In acne, it is the serious condition that develops when plugged follicles rupture to cause deep swelling, pain, and redness. In severe cases, these cysts and nodules result in scarring. (See Acne, Blackheads, Comedones, and Whiteheads.)

Cytokines - A group of soluble, hormone-like proteins produced by white blood cells that act as messengers between cells. Cytokines regulate the intensity and duration of immune responses and are involved in cell-to-cell communication. To a large extent, cytokines mediate inflammatory responses.

Dandruff - An itchy, annoying persistent skin disorder of the scalp characterized be abnormal shedding of dead scalp skin cells. Condition where dead cells shed from the scalp. Most skin specialists agree dandruff is associated with a tiny fungus called Pityrosporum ovale (P. ovale), which are always present on the scalp, but in certain individuals and at certain times become more opportunistic resulting in mass disorder/shedding.

Defense Mechanism - Term used to describe ways body protects itself from different forms of attack. Often the immune response to offending substances such as bacteria, allergens, microbes, and pain.

Degradation - A progressive decline of a substance. In skin care, it refers to breakdown of structural skin components such as collagen, elastin, and cell membranes.

Denature - To alter or structurally change a protein usually by heat, acids, bases, or detergents.

Dendrite - A treelike branching arm of a neuron (nerve cell) that transports materials from one cell to another. They are receptors of electrochemical nervous impulse transmissions.

Depilatory - A cosmetic product used to remove unwanted hair from the body.

Dermal Crease - Area of the skin where repetitive mechanical muscle movement causes protein (collagen and elastin) to breakdown and skin to collapse along certain lines—typically around the mouth, nose, eyes, and forehead—with time forming deep lines and wrinkles.

Dermatologist - A physician who specializes in the study, diagnosis, and treatment of skin disorders.

Dermis - The sensitive layer of skin (below the epidermis and above the subcutaneous layer) made up of connective tissue, sensitive nerve endings, blood and lymph vessels, hair follicles, sweat glands, collagen bundles, elastin fibers, and fibroblasts. Also known as corium. (See Epidermis and Subcutaneous.)

Dermatitis - An inflammation of the skin caused by an allergic reaction or contact with an irritant. Sometimes called eczema. Typical symptoms of dermatitis include redness and itching. Often broken into subcategories: (1) contact dermatitis—irritation that arises from direct contact with a material (this can be an immune response, such as an allergic reaction to latex), (2) atopic dermatitis is often found in the face, elbow, and knee flexures of infants; symptoms tend to disappear with age.

DHT - Dihydrotestosterine (DHT) is the active form of the male hormone, testosterone, produced from testosterone by an enzyme known as 5-alpha reductase. Male and female pattern hair loss is thought to be due to the effects of DHT on genetically predisposed hair follicles. DHT causes increase in sebum production and hence plays a role in acne for some individuals. It also inhibits elastin production by blocking the receptor.

Diffusion - Movement of suspended or dissolved particles from a more concentrated to a less concentrated area. The process tends to distribute the particles more uniformly.

Dilate - In biology, term used to describe the relaxing or expanding of blood vessels that open or speed up blood flow. When blood vessels dilate or open in the skin, for example, blushing appears.

Discoloration - In skin care, it describes uneven skin tone, brown spots, blotchy skin, freckles, or age spots due to accumulation of melanin. Cause by UV damage, hormones, acne, disease, or stress.

DNA - Deoxyribonucleic acid (DNA), a double-stranded, helical molecular chain found within the nucleus of most living cells. It carries genetic information that encodes proteins and enables cells to reproduce and perform their functions.

Dopa - An amino acid. In skin pigmentation pathway, it is an intermediary molecule in melanin synthesis. The enzyme tyrosinase converts tyrosine (another amino acid) into dopa, which is then converted to dopaquinone and eventually to the skin pigment melanin. (See Melanin and Tyrosine.)

Dopaquinone - Produced by the amino acid dopa; is a precursor molecule to melanin in the synthesis of skin pigment.

Dose-Response Study - A test designed to determine the optimal level of an specific substance or active ingredient by measuring its effectiveness at different concentrations.

Eccrine Sweat Gland - Sweat gland located in the dermis. Helps regulate body temperature by manufacturing and excreting sweat onto the skin’s surface. Found all over the surface of the body. (See Sweat Glands.)

Eczema - A chronic skin condition characterized by inflammation and red, crusty, scaly, and itchy patches of skin. Atopic dermatitis is often found in the face, elbow and knee flexures of infants; symptoms tend to disappear with age. (See Dermatitis.)

Efficacious - Having the ability or power to produce a desired effect. In cosmetics, refers to products that provide benefits.

Elastin Tissue Content - The concentration of the structural skin protein elastin, found in the dermal layer of the skin.

Elasticity - The degree to which the skin is capable of retaining or returning to its original state in the midst of aging, weather, biological events (e.g., pregnancy), and other factors.

Elastin - A coiled protein in the dermis that gives the skin its elasticity and ability to return to its original shape.

Elastinase - An enzyme that breaks down the skin protein elastin.

Emollient - An externally applied agent that softens or soothes skin and helps prevent water loss.

Enamel - The visible outer layer of the tooth.

Endonuclease - A protein enzyme that breaks down bonds between nucleic acids at specific nucleotide sequences of DNA, making it possible to isolate desired DNA fragments.

Environmental Aging - The process of getting older due to daily exposure to sunlight, pollution, and weather extremes. Also known at extrinsic aging. (See also Biological and Mechanical Aging.)

Environmental Stress - Disruption or upsetting of the skin's natural balance in response to adverse environmental conditions such as UV radiation, extreme weather conditions, and pollution, causing premature aging, discoloration, acne, and other skin conditions.

Enzyme - Proteins produced by the body that function as catalysts to speed up and direct natural chemical reactions within the body. Without enzymes, chemical reactions would take place at such a slow rate that organisms would not be able to execute normal life functions.

Epidermis - The outer protective layer of skin consisting mostly of keratinocytes (skin cells). Can be divided into sublayers based on keratinocyte "birth to cell death" morphology. The deepest layer or basal layer is home to melanocytes that produce melanin and continuously dividing cells that form new keratinocytes. The next layer is the spinous layer, where mature keratinocytes stop dividing and begin to change shape and move to the granular layer, where the keratinocytes begin to breakdown and form keratin granules. The top layer or stratum corneum continually sheds dead, cornified keratinocytes and provides a protective keratin protein barrier. The keratinocyte migration from basal layer to stratum corneum takes about 14–30 days. (See Basal Layer, Dermis, and Keratinocyte.)

Equilibrium - A condition of balance within the body resulting in a stable or unchanging environment.

Essence - A concentrated extract that provides a specific benefit or aroma.

Ethnobotanical - A plant or plant extract known for their indigenous uses and benefits.

Ethnobotany - The study of the plant lore and agricultural customs of a people.

Excretion - General term for removal of substances from the body. The sweat and oil glands are excretory organs.

Exfoliant - A small inert particle or chemical agent known to accelerate dead skin cell removal from the skin's surface.

Exfoliation - The process of removing the top layers of dead skin cells using chemical or mechanical agents. Exfoliation encourages skin renewal.

Expression Phase - Term used to describe third phases of skin discoloration process where melanin is brought to the skin's surface and made visible. Keratinocytes receive melanin packets from melanocytes, and as cell renewal occurs, keratinocytes migrate to the top layer of the epidermis making the melanin visible to the naked eye. (See Activation Phase, Keratinocytes, Synthesis Phase, and Melanin.)

Extracellular Matrix - The shapeless substance that bathes the structural components of the dermis (collagen, elastin, fibroblasts.) It is composed mostly of glycosaminoglycans (GAGs). A complex, multi-molecular material that surrounds cells. Composed mostly of ceramides, cholesterol esters, and fatty acids helps to maintain soft and healthy skin. Also known as intercellular matrix.

Extract - A concentrate of desired constituents taken from a plant through physical and/or chemical means. Used in cosmetic formulations for scent, healing properties, or other benefits.

Fatty Acids - A basic unit of fats required for the health of cell membranes and the moisture barrier of the skin. Fatty acids frequently occur in the form of esters and glycerides. As ingredients of skin care, essential fatty acids can replenish skin with essential lipids and restore barrier function.

FDA - The federal agency responsible for regulating the safety and efficacy of food and drugs sold in the United States of America. Certain over the counter (OTC) cosmetic drugs are also regulated by this agency, also known as the USA FDA. (See OTC Drugs.)

Fermentation - Chemical changes in organic substances produced by the action of enzymes or certain microorganisms.

Fibroblast - A specialized cell within the dermis that produces the structural proteins elastin and collagen in connective tissue.

Flora - In biology, the naturally occurring bacteria on the skin, in the mouth, or in other organs of the body.

Food Starch - A complex carbohydrate that is the most common storage product in plants. Found in fruits, seeds, potatoes, rice, and wheat.

Formula - A recipe of ingredients in specified proportions that produces the bulk or composition of a product.

Fragrance-Free - A product that contains no fragrance ingredients.

Freckle - Small brownish spot of melanin on human skin in people of fair complexion, predominantly found on the face. Predisposition to freckles is genetic, though exposure to sunlight is a factor in how many appear. The gene for freckling is related to the presence of red hair.

Free Radicals - Molecules or ions with unpaired electrons, that are highly reactive and can oxidize other molecules. These oxidants can cause cellular damage and contribute to a disease process. Free radicals occur in the body through normal aerobic respiration, metabolism, and inflammation; environmental factors outside the body that can cause free radical production include pollution and sunlight. Antioxidants are thought to combat the negative effects of free radicals. (See Antioxidants.)

Free Radical Chain Reaction - The continuing process in which one free radical causes a stable atom to become another free radical and so on. This cycle continues perpetuating potentially harmful levels of free radicals.

Fungi - Plantlike organisms that lack chlorophyll and must take nutrients from their environment rather than make their own food. They include mushrooms and molds.

Galvanic Current - Another term for direct current (DC), which is the continuous flow of electric charge through a conductor from high to low potential. In DC the electric charges flow always in the same direction, which distinguishes it from alternating current (AC). Galvanic current is used in the Nu Skin® Galvanic Spa Instruments.

Germs - Term used to describe microorganisms that cause disease or illness.

Glucosaminoglycans - Long unbranched polysaccharides (sugar chains) characterized by their rigidity. Primarily located on the surface of cells or in the extracellular matrix (ECM). Provide structural integrity to cells.

Gums - The connective tissue in the mouth that surrounds teeth.

Hair Follicle - A tiny tubular structure in the skin, contiguous with the top skin layer, or epidermis, that includes the canal, the hair shaft, the sebaceous (oil) gland, and the muscle anchored to the follicle's side wall. The follicle extends into the dermis, providing hair roots with a blood supply to grow.

Hair Shaft - The hair shaft is the part of the hair that protrudes from the skin.

Herbal - Refers to substances derived from herbs or herb parts. A herb-based product often used for its aroma and/or healing properties.

Homogenization - The act of making something uniform in composition and improving consistency.

Hormone - A substance, usually a peptide or steroid, produced and secreted by the endocrine glands. Hormones travel through the bloodstream to effect specific physiological activity or effects in the body, such as growth or metabolism.

Hormone Initiators - Substances or environments that trigger hormone production.

Hormone Receptor - A molecular structure or site on the surface or interior of a cell that binds with hormones. Once the hormones are bound to the receptor, specific functions within the cell are signaled to begin.

Humectant - A substance that absorbs or retains moisture. An ingredient that helps the skin retain moisture. Glycerin is one of the more typical and effective humectants.

Humidity - The measure of water in the atmosphere. Complete saturation is designated by 100% humidity, meaning the air cannot hold anymore water without precipitation.

Hydration - The process of restoring or maintaining water balance. Hydration is important in personal care products because moisture is essential for good skin and hair health.

Hydrogen Ion - A positively charged chemical species (H+) formed when hydrogen loses an electron. It is the ionized form of the hydrogen atom. Created when acids are placed in an aqueous solution.

Hydroxyl Group - Negatively charged chemical species consisting of oxygen and hydrogen (OH-). Created when bases are placed in an aqueous solution. Reacts easily with hydrogen ions (H+) to form water (H₂O).

Hyperpigmentation - Increased coloration or melanin of the skin often seen as dark spots or areas. Can be caused by UV exposure, stress, or hormones and may be related to inflammatory response, skin irritation, trauma, or some disease process.

Hypoglycemia - A condition when glucose (sugar) is abnormally low in the blood.

Hypothyroidism - A thyroid gland disease causing insufficient production of thyroid hormones, which regulate metabolism (the conversion of food into cellular energy).

Ichthyosis - A rare genetic skin disease evidenced by dry, scaly skin. It is a disorder of keratinization as characterized by excessive scales or keratinized skin cells in the stratum corneum. There are treatments, but no known cure.

Immune Function - Production and action of cells that fight disease or infection. The system that fights infection and assaults to the body.

Indigenous - Original and native to an environment or area.

Inflammatory Response - Complex response of tissues to injury, characterized by immune system activation and local production of inflammatory mediators. The reaction is characterized by pain, redness, swelling, and sometimes itching in an area of exposure.

In-House Study - A scientific study performed and conducted locally by Nu Skin research and development department.

Inorganic - Substances that are of mineral or non-biological origin, whereas organic substances are usually of animal or plant origin. Composed of matter other than hydrocarbons and their derivatives, or matter that is not of plant or animal origin. Typically, chemicals that do not contain carbon atoms.

Intercellular Matrix - See Extracellular Matrix.

Ions - Electrically-charged atoms or molecules due to gain or loss of electrons. Positive ions are called cations and negative ions are called anions.

Irritant - A substance that consistently and predictably produces an adverse response. It can be a non-corrosive chemical that causes tissue inflammation at the site of contact such as reddening, swelling, itching, burning, or blistering or a physical agent causing chafing, soreness, or inflammation. Irritants are not to be confused with allergens, which induce a different cascade of reactions.

Irritation Initiator - A substance or agent that triggers adverse response. (See Irritant.)

Kelp - Large brown seaweed (brown algae) with high mineral and nutrient content. Used in skin care products as conditioning, water binding and antioxidant agents. (See Algae.)

Keratin - A tough protein that is the primary constituent of hair, nails, and skin.

Keratinocyte - A skin cell that comprises 90% of the epidermis (the top layer of skin). They form and divide in the epidermal basal layer. As mature cells they migrate to the epidermal spinous layer where they change shape and no longer divide. Then, they move to the epidermal granular layer and stratum corneum where they break down, die and are shed. This last step is called cornification and is where the keratinocytes are finally transformed into keratinized horny material. It takes 14–30 days for a keratinocyte to make the transition and transform to tough keratin in the top layer before being shed. (See Basal Layer, epidermis, and Stratum Corneum)

Lecithin - A naturally occurring phosolipid emulsifier, emollient and antioxidant. A major component of cell membranes. It can be produced from egg yolk and soybeans and is used in a variety of pharmaceuticals, foods, and cosmetics.

Lipid - Descriptive term for fat or fat-like substance such as cholesterol found in the blood and cellular membranes. Can be an energy source for the body. Important lipids include fatty acids (saturated and unsaturated) and phospholipids (main component of biological membranes) and sterols like cholesterol. Lipids are water insoluble (hydrophobic) and used on the skin as moisturizer and emollients to help protect from harsh environmental stressors.

Litmus Paper - Special paper that indicates how acidic or basic an object or liquid is. Litmus is a water-soluble blue powder derived from lichens that is absorbed into porous paper. Litmus paper turns red in the presence of acids and turns blue in the presence of alkalines or bases.

Luminous - In skin care, a description of a clear, radiant complexion, a fresh glow.

Lymph Vessels - Enclosed network of tubes (the lymphatic system) that transports a fluid known as lymph around the body. Lymph consists of the fluid that bathes the tissues, protein, fat, and white blood cells. The lymphatic system filters this fluid and returns it to the blood stream, and also plays an important role in the immune system.

Lyse - To cause or produce disintegration of a compound, substance, or cell such as destruction of red blood cells, bacteria, or microorganisms.

Marine Diatoms - A type of algae which produce an external skeleton made of silica that is often preserved in great numbers in lake sediments. Used in cosmetics for exfoliation. (See Algae and Exfoliation.)

Marine Phytoplankton - See Algae.

Market Potential - Potential, achievable sales volumes within a specific time period and market.

Matte Finish - In cosmetics, having a non-shiny or non-oily skin appearance.

Mechanical Aging - The process of getting older due to habitual muscle movements, either stretching or compressing the skin repeatedly, including squinting, smiling, scrubbing or rubbing your face with force, and sleeping on your side. Most notable in deep lines and wrinkles in the forehead and nasolabial folds of the face. (See also biological and environmental.)

Mechanical Exfoliation - The process of removing the top layers of dead skin cells using physical agents. Exfoliation encourages skin renewal by smoothing wrinkles and evening texture.

Mechanical Stress - See Mechanical Aging.

Medical-Grade - Meets USA FDA standards for safety and efficacy.

Melanin - The pigment that gives skin, hair, and eyes their color. Melanin synthesis occurs in the melanocytes found in the basal layer of the epidermis. Production is triggered when UV light and other aggressors stimulate release of irritation, stress, or hormone initiators that bind to melanocyte receptors and stimulate melanin production. Through a series of chemical conversions, one of two forms of melanin is made: eumelanin (black or brown pigment) and pheomelanin (yellow pigment). (See Dopa and Tyrosine.)

Melanocyte - A skin cell found in the basal layer of the epidermis that produces melanin when triggered by factors such as UV light, effecting skin discoloration. (See dopa, melanin, and tyrosine.)

Melanosome - A membrane-bound vesicle of melanin in a melanocyte that transports the melanin through to the keratinocytes.

Melasma - Symmetrical patches of brown pigment on the face also know as "mask of pregnancy." Most often seen in females and can be exacerbated by estrogen and sunlight.

Metabolize - Process of breaking down substances in cells to obtain energy. (See Cellular Energy and Cellular Respiration.)

Microalgae - Another term for algae. (See Algae.)

Microbial Resistance - The ability of micro-organisms to resist being killed by an anti-microbial agent. Over time microbes develop an immunity or a resistance to antibacterial agents, such as overuse of antibiotics.

Microcrystals - Tiny crystals like aluminum oxide used in microdermabrasion.

Microdermabrasion - A facial mini-peel or mini-sanding technique used to remove the top layers of skin using either chemicals or abrasive agents such as diamond dust or aluminum oxide crystals. A popular non-surgical, cosmetic procedure performed by an aesthetician to lessen the appearance of facial wrinkles and improve the aging appearance of the skin. The results remain for three to six weeks before it needs to be repeated.

Microfine Antiperspirant - Ingredient particles of smaller than standard size, allowing for better absorption/penetration. Provide improved perspiration and deodorant control.

Mid Note - In fragrance, the mid note is a term used to describe the "bouquet" that emerges as the fragrance is blended with your skin and body chemistry. Usually takes 10–20 minutes to fully develop on the skin. (See Base Note and Top Note.)

Moisture Barrier - See Barrier Function.

Moisturization - In skin care, the process of providing and helping barrier function, softness, and health. (See Barrier Function.)

Molecular Weight - The sum of the atomic weights of all of the elements in the compound

Molecule - Two or more atoms joined together by chemical bonds.

MSH - Melanocyte Stimulating Hormone (MSH) is a peptide hormone produced by the pituitary gland. When body is exposed to sunlight MSH is produced to stimulates production and release of melanin (melanogenesis) by melanocytes in skin and hair. (See Melanin and Pigmentation.)

Negatively Charged - Refer to an atom or molecule that carries a negative ion due to the loss of an electron.

Non-Aerosol - Describes a cosmetic product delivery system without gas propellant.

Non-Feathering - Term used in color cosmetics that refers to lip products that do not "bleed" or feather into the fine lines and wrinkles around the mouth.

Nucleus - In biology, it is an organelle found in most cells that contains genetic material or DNA. It has two primary functions: to control chemical reactions within the cell and store information for cell division. (See DNA.)

Oil Glands - Produce an oily substance called sebum, which is secreted to the skin surface via a duct. Called sebaceous glands, they are found in hair follicles throughout the body except in the soles of the feet and palms of the hands. Sebum helps keep skin soft and supple. Excessive sebum production promotes development of acne. (See Acne.)

Organic - Class of chemical compounds having a carbon basis, often plant or animal derived. In consumer products, the US FDA regulates that "organic" consumables are grown without chemical fertilizers or pesticides.

OTC Drugs - Over the counter (OTC) drugs are products that can be purchased without a physician's prescription and are intended to treat or prevent disease or otherwise affect the structure or functions of the human body. Regulated by the FDA in the USA. Fluoride toothpaste, sunscreens, and antimicrobials are OTC products.

Oxidative Stress - Accumulation of destructive molecules called free radicals that can damage cells membranes, proteins, or genetic material by "oxidizing" them. Fire and rust are both examples of oxidation as is butter (or any fat or oil) turning rancid. Antioxidants inhibit oxidation, and thus protect the oil phase of cosmetics from becoming rancid. (See Free Radicals.)

Oxidize - To combine or cause to combine with oxygen. Loose electrons often produce free radicals.

Oxygen Radical Absorptive Capacity (ORAC) - Measure developed by researchers to describe the antioxidant levels of fruits and vegetables. Berries, for example, have the highest ORAC of any fresh fruit.

Patented - A product or technology with exclusive rights of ownership granted by a government to an inventor or applicant for a limited amount of time (normally 20 years). Protection of intellectual property. Exclusive rights to manufacture, use, and sell.

Pearlescent - A term used to describe a surface or liquid with lustrous, cloudy, rainbow-like colors like one might see in mother of pearl. A milky opalescent (or opaline) luster. Synonymous with iridescent.

Pentapeptides - Five amino acids bonded together. Can function as chemical messenger. Used in anti-aging skin care as pro-collagen ingredient to diminish the appearance of wrinkles.

Peptide - Two or more amino acids bonded together. Can function as a chemical communicator. Small peptides are used in skin care because they can be easily absorbed into the skin.

Peptide Bond - Chemical link joining amino acids. When peptide bonds in the hair are broken, hair is damaged.

Permeability - A measure of rate of flow/diffusion of gas or liquid through a membrane. (See Diffusion.)

Peroxides - Category of compounds containing an unstable Oxygen to Oxygen or O–O Group: often used to bleach teeth, but can weaken tooth enamel and irritate soft mouth tissue.

pH Scale - The scale used to measure acidity or alkalinity of a solution. The pH scale ranges from 0 to 14 (7 being neutral; 0–7 being acidic; 7–14 being alkaline). Healthy skin is slightly acidic, pH between 5.5 and 6.5. (Also see Acid, Alkaline, and Base.)

pH Balanced - A substance that has its optimal pH level.

Pharmaceutical - Substance or drug dealing with the prevention or cure of disease or disorders.

Phospholipids - See Lecithin.

Phospholipid Bilayer - See Cell Membrane.

Photoprotective Pigment - A substance that produces a characteristic color and is able to absorb UV radiation and protect cellular structures. Carotenoids, chlorophyll, and melanin are photoprotective pigments.

Photosynthetic - Describes the process that converts light energy to chemical energy. Where cells in the presence of chlorophyll are able to produce carbohydrates from carbon dioxide.

Phytochemical - A chemical found in plant sources.

Pigment - A substance, such as chlorophyll or melanin, that produces a characteristic color in plant or animal tissue.

Pigmentation - The deposition of pigment in animals or plants or human beings. The natural process of synthesizing and distributing pigment (melanin) to the surface of the skin, giving the skin color and tone.

Pimple - A small swelling of the skin, usually in the form of a whitehead or blackhead. Associated with acne. (See Acne, Blackheads, Comedones, and Whiteheads.)

Plaque - In oral care, a bacteria-containing substance that collects on the surface of teeth. Plaque can cause decay and gum irritation when not removed by daily brushing and flossing. In medicine, a deposit of fatty (and other) substances in the inner lining of the artery wall characteristic of atherosclerosis or heart disease.

Plasticity - The quality of being elastic, pliable, and soft.

Plexiglas - A trademarked transparent, lightweight, and weather-resistant thermoplastic. Used to demonstrate the abrasive effects of microdermabrasion and NuSkin® Polishing Peel.

Polish - To bring to a highly developed, finished, or refined state. The property of being smooth.

Pollution - Release of harmful environmental contaminants to air, water, or soil. An undesirable change in the physical, chemical, or biological characteristics of the environment. Unwanted chemicals or other materials found in the air.

Polyhydroxy Acid (PHA) - PHAs are chemically and functionally similar to AHAs. However, PHAs are larger molecular structures, which limits their ability to penetrate into the skin, resulting in a reduction of irritating side-effects. Besides penetrating the skin more gently, they have multiple hydroxyls, which make them strong humectants. When compared to traditional AHAs, they are equally effective at increasing skin cell renewal, normalizing stratum corneum exfoliation and thickness, and conditioning the barrier function. PHAs offer a distinct advantage over conventional AHAs for sensitive skin conditions such as rosacea, atopic dermatitis, eczema, seborrhea, or ichthyosis. (See AHAs.)

Polyphenols - Very powerful antioxidants, present in several different botanicals, most notably grape skin, grape seed extracts, and olive oil. Characterized by the presence of more than one phenolic group. Responsible for the coloring of some plants.

Polysaccharide - A biological polymer composed of sugar subunits for example, starch or cellulose. A complex carbohydrate that contains simple sugar molecules linked together chemically. In skin care, provides conditioning and moisturizing properties.

Pore - A minute opening in the skin to the pilosebaceous unit (oil gland and hair follicle). Blocked pores can result in acne. (See Acne.)

Pore Prominence - A measure of pore size. (See Pore.)

Porphyrin - Protein pigment excreted by bacteria which can be detected under special light, indicating areas of high bacteria count.

Positively Charged - Refers to an atom or molecule that carries a positive ion due to electron gain.

Poultice - A soft mass, sometimes heated, then spread on a clean cloth and applied to sores, aches, sprains, or wounds in general. It is to ease pain and reduce inflammation.

Preservative - A substance added to food and cosmetic products to inhibit the growth of bacteria, mold, and fungus and preserve product freshness and integrity.

Pro-Collagen Peptide - Selected amino acids bonded together designed to up-regulate collagen production in the skin. Pentapeptide is a pro-collagen peptide. (See Pentapeptide.)

Pro-Oxidant Metals - Easily oxidized metals that bind with oxygen. During oxidation, free radicals that damage skin are generated. (See Free Radicals.)

Proprietary Ingredient - A material that is exclusively owned by a single company that carefully guards the knowledge. No other company can use this material or technology in a product.

Protease - An enzyme that digests proteins and breaks down amino acids by hydrolyzing peptide bonds. These enzymes are often used to soften skin and clear skin surface of cellular debris. Examples are brornelain (from pineapple) and papain (from papaya).

Protein - Amino acids bound together by peptide bonds into one molecule. Proteins are vital to tissue growth and repair.

Proteolytic Enzyme - See Protease.

Radiance - The fresh, youthful appearance of skin, free from dull, dry, dead cell build up.

Razor Bumps - This condition is called "pseudo" folliculitis because it is caused not by a bacterial infection, but by the regrowth of hair after it has been shaved. Occurs most often in people with very curly, kinky hair. The technical name for razor bumps is pseudofolliculitis barbae (often abbreviated PFB).

Razor Glide - The ease with which the blade of a razor pulls across the skin. Poor razor glide can often irritate the skin, resulting in redness and rashy appearance.

Receptor Site - A molecular structure within a cell or on cell surface where selective binding of a specific substance causes a specific physiologic effect. Often receptor sites are proteins that bind hormones, antigens, drugs, or neurotransmitters that transmit information to the cell.

Refinish - In skin care, refers to the process of removing dry, uneven dead skin to create a smooth, even finished, or refined texture.

Regimen - A a group of products applied systematically to provide desired benefits. Typical basic skin care regimens include a cleanser, toner, serum, sun protection, and moisturizer.

Renewable Resources - Naturally recurring sources of energy, elements, and materials, that can be replaced or replenished at a rate equal to or greater than its rate of depletion.

Resilience - In skin care, refers to the skin's ability to recover in relation to aging, wear, and stressors. Also, can mean the skin's flexibility or elasticity.

Retexturization - The process where uneven, rough skin is physically or chemically exfoliated to promote smooth, even, soft skin. (See Exfoliation and Microdermabrasion.)

Rosacea - A chronic, inflammatory skin disorder that causes flushing and, eventually, permanent patches of red skin on the nose and cheeks and acne-like bumps. Involves enlargement of blood vessels under the skin on cheeks, nose, chin, forehead, or eyelids. Symptoms include redness, increased prominence of the blood vessels, swelling of the tissue, and skin eruptions similar to acne. Occurs most often in fair skinned women, particularly those who blush easily.

Ruddy - Description of coarseness or redness in the complexion.

Safety-Allergy-Dermatologist Tested - A product claim that certifies the safety of formula as determined by dermatologist monitored test called a Repeat Insults Patch Test ( RIPT). Passing results from a RIPT ensures product safety for the majority of skin types. A third party laboratory follows a standard, controlled protocol, where a small amount of product is repeatedly applied to the test subject skin, and its effects are monitored, evaluated and approved or not approved by a dermatologist.

Sallow - Unhealthy looking. A dull, yellowish complexion hue, possibly due to poor nutrition, exposure to UV light, or decrease in skin cell turnover.

Sanitize - To sterilize or clean.

Scalp - The layer of skin covering the head, usually containing a high concentration of hair follicles.

Sebaceous Gland - See Oil Gland.

Seborrheic Dermatitis - An inflammation of the upper layers of the skin where scales appear on the scalp, face, and sometimes in other areas. Usually more common in cold weather and often runs in families. Dandruff is mild seborrheic dermatitis of the scalp. Seborrheic dermatitis is thought to be caused by a fungal infection caused by the yeast Pityrosporum ovale in individuals with decreased immunity and increased sebum production. (See Dandruff.)

Sebum - Oily substance produced by sebaceous (oil) glands in the skin. Composed primarily of fat, keratin, and cellular material. (See Oil Glands.)

Sensitive Skin - Description of skin highly responsive to particular agents/stimuli. Also known as allergic skin. Recommend careful adoption and monitoring of new skin care products to daily regimen. (See Inflammatory Response, Irritation, and Regimen.)

Skin - The largest organ of the body, which consists of two main layers—the epidermis and dermis—that function to protect the body. (See Epidermis and Dermis.)

Skin Barrier Function - See Barrier Function.

Skin Cancer - A harmful, malignant growth on the skin, which can be caused repeated severe sunburns or long-term exposure to the sun. There are three common types of skin cancer, each named after the skin cell type: basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.

Skin Cell Renewal - See Cell Renewal.

Skin Type - Typically refers to texture and complexion of skin such as sensitive, normal, dry, oily, combination, sensitive, etc. Cosmetic products cannot change skin type, but can be formulated to benefit specific skin types. Dermatologist use the Fitzpatrick Classification for Sun-Reactive Skin Types to analytically determine potential sensitivity to sun exposure. The Fitzpatrick scale goes from I to VI, where I is caucasian, blonde/red hair, freckles, fair skin, blue eyes, very sensitive to sun, always burns easily, never tans, very fair skin tone; and VI is dark-skinned, least sensitive to sun, never burns, deeply pigmented, very dark skin tone.

Sloughing - In skin exfoliation, it is the shedding of dead skin cells.

Soap-Free - Term used to describe mild cleaning agents that are not produced from a reaction of fat and alkali (soap). Soap-free cleansers have pH levels closer to skin whereas soap have an alkaline or high pH. (See Acid, Base, and pH Scale.)

SPF - Sun Protection Factor (SPF) is a world-wide rating system for measuring the amount of protection offered by a sunscreen lotion. It indicates how long an individual can remain in the sun using sunscreen without burning. SPF usually allows one to stay in the sun 10 times longer than without burning. For example, if an individual normally begins to burn after 10 minutes in the sun, they would be able to remain in the sun 150 minutes before beginning to burn when using a SPF 15 sunscreen (10 x 15 = 150). SPF is not a linear scale so sunscreens with SPFs over 30 do not give any measurable protection higher than 30. (See Broad Spectrum Protection, UVA, and UVB.)

Split Ends - Referring to hair, brittle and rough ends and strands of hair that occur with dryness and hair damage.

Split-Face Study - A clinical test where the human subject tests one material on half of the face and a different material (or nothing if side is baseline control) to the other half of the face. (See Clinical Study.)

Static Electricity - Condition caused usually when materials rub against each other, creating an unequal distribution of electrons that leads to a spark or magnetic reaction.

Stimuli - Agents or conditions that cause physiological activity or response.

Stratum Corneum - Also known as the horny layer, the stratum corneum is the top layer of the epidermis that contains continually shedding, dead keratinocytes called corneocytes. (See Corneocytes, Epidermis, and Keratinocytes.)

Stress Initiators - External or internal factors that disrupt balance and equilibrium. In skin, these factors can cause an inflammatory or irritation response.

Striations - Referring to cellulite, striations are bands of disfiguration that can be seen on the surface of the skin. (See Cellulite.)

Subcutaneous Layer - Lying below or under the dermis (cutaneous) tissue. Refers to the layer of connective tissue and fat cells beneath the skin. (See Dermis and Epidermis.)

Sunscreen - A substance that helps protect skin from the sun's harmful rays. Sunscreens reflect, absorb, and scatter both ultraviolet A (UVA) and ultraviolet B (UVB) radiation. Sunscreen products specify SPF, and dermatologists recommend using a broad-spectrum sunscreen with at least SPF 15 on all exposed skin, including the lips, even on cloudy days. Sunscreens cannot protect from all negative effects of the sun. (See SPF, UVA, and UVB.)

Surfactant - A surface-active agent that reduces the surface tension of two liquids. Usually an organic compound that contains a hydrophilic (water-loving) group and a lipophilic (fat-loving) group, giving it the ability to surround and rinse away dirt, oil, and pollution. Also known as wetting agents, surfactants provide spreading or emulsification due to lower surface tension.

Sweat Glands - Located in the dermis. Helps regulate body temperature by manufacturing and excreting sweat onto the skin’s surface. Found all over the surface of the body. (See Eccrine Sweat Gland.)

Sympathetic Nervous System - A part of the autonomic nervous system over which a person does not have conscious control. It regulates tissues such as glands, heart, blood vessels and smooth muscle. Responsible for mobilizing the body’s energy when stressed or aroused.

Synergistic - The action of two or more substances achieving an effect greater than that possible with any of the individual components.

Synthesis Phase - The second phase of skin pigmentation. In this phase, tyrosinase, an enzyme, triggers the production of melanin in a melanocyte. Tyrosine, an amino acid, goes through a series of reactions to become one of two forms of melanin: eumelanin or phaemelanin. (See Activation Phase, Expression Phase, and Tyrosinase.)

Synthetic - Substances artificially produced by chemical or biochemical means. Often man-made, but having the same physical, chemical and optical characteristics as the natural material.

Systemic Antibiotics - Medications administered as a capsule, pill, tablet, or liquid in the treatment of a bacterial infection. Also called, oral antibiotics. Dermatologist may prescribed for the treatment of chronic, cystic acne.

Tan - A darkening of the skin caused by increased melanin production. A browning of the skin resulting from exposure to the rays of the sun. Often considered the skin's defense mechanism to sun damage. (See Pigmentation and Melanin.)

Tannin - A brown pigment found in leaves and other parts of plants. It is the bitter-tasting, mouth puckering, astringent in strong tea. As a group they are a complex mixture of polyphenols.

Tanning Methods - Refers to techniques uses to increased skin pigmentation such as tanning salons with UV light beds, laying out in the sun, and using substances such as suntan oil. (See Tan and Pigmentation.)

Tearless - A cosmetic product that does not cause eye sting or irritation. Must pass special safety testing by third party laboratory to make this claim.

Terpenoids - Largest group of natural products. For example, several vitamins, hormones, flavor and flagrances, and biopolymers (latex) are terpenoids. Because terpenoids or terpenes are biologically active compounds, they are also employed for medical purposes.

Texture - The characteristic appearance of a surface having a tactile quality. In skin, it describes the surface appearance— rough, smooth, thin, thick, scarred, etc.

Therapeutic - Pertaining to treatment. Relating to the remediation or cure of a disorder or disease. Having a quality of healing.

Thermogenesis - Production of heat, especially by the cells of the body.

Thermoregulation - The regulation of body temperature. Ability of an organism to keep its body temperature within certain boundaries, even when temperature surrounding is very different.

Third Party Clinical Study - Test conducted by laboratory or testing facility not associated with and independent from Nu Skin Enterprises.

Tone - Quality of color and elasticity with regard to skin. The act of using a toner product.

Toner - Product designed to diminish the appearance of pores and restore ideal pH level to the skin.

Top Note - In fragrance, the top note is the initial impact or first sensory/smell experience. This sensation can last 5–10 minutes, compelling the consumer to further enjoy the fragrance experience. (See Base Note and Mid Note.)

Topical - A product that is applied externally to the skin.

Trans-Epidermal Water Loss (TEWL) - Trans-epidermal water loss (TEWL) is the water release from the skin layers (epidermis). A TEWL test accurately gauges stratum corneum or barrier function integrity. An evaporimeter is used to determine evaporation of water from the surface of the skin and the skin temperature. (See Barrier Function and Epidermis)

Toxin - A substance that causes injury to the health of a living thing on contact or absorption.

Tri-Phasic - A term used to describe the three phases of skin discoloration. The phases are activation, synthesis, and expression.

Tyrosinase - Tyrosinase is an enzyme that triggers the production of melanin from tyrosine. (See Tyrosine.)

Tyrosine - An amino acid small amounts in most proteins. It can be activated by the enzyme tyrosinase to dopa, which is then converted to dopaquinone and eventually to the skin pigment melanin. (See Dopa and Melanin.)

Ultraviolet Radiation - Ultraviolet radiation from the sun consists of three bands: UVA, UVB, and UVC. UVC rays are mostly filtered out by the atmosphere, but UVA and UVB rays reach the earth strongest between 10 a.m. and 2 p.m. These rays can affect people directly as well as through reflection (off of water, snow, cement, grass, etc.). (See UVA and UVB.)

UV Light - UV or ultraviolet light has wave lengths shorter than visible light and longer than x-rays. Ultraviolet literally means beyond violet—violet being at the top end of visible light’s color spectrum. UV light exposure can damage skin over time and cause skin cancer. Sunscreen can reduce the impact of exposure by blocking some of these rays and is rated by SPF (see Sun Protection Factor). UV light may be responsible for as much as 75 percent of skin aging.

UVA - Ultraviolet light type A (UVA) are rays of light from the sun which are not visible but can cause damage to the skin. They are thought to be the most harmful UV rays and are the main cause of photo aging, eye damage, and skin cancer. They have short wavelengths—320 to 400 nanometers—and can also pass through glass to impact skin. Some sunscreens do not block UVA rays. (See Broad Spectrum Protection, SPF, and UVB.)

UVB - Ultraviolet light type B (UVB) are rays of light from the sun which are not visible but can cause damage to the skin. UVB rays are the UV rays associated with sunburn. Many UVB rays are filtered by the ozone layer and cannot pass through glass. Most sunscreens will protect skin from UVB rays and therefore provide protection from sunburn. They have short wavelengths—280 to 320 nanometers—and are readily affected by ozone levels. Decreases in ozone levels lead to increase UVB radiation reaching the earth. Increased UVB leads to a variety of skin problems including sunburn, skin cancer, and premature aging. (See Broad Spectrum Protection, SPF, and UVA.)

Vitality - The youthful properties of health or skin. Full of life.

Vitamin - A group of organic micronutrients (present in minute quantities in natural foodstuffs) that are essential to normal metabolism.

Waterless - A product, such as hand sanitizers, where water is not needed for product usage.

Waterproof - Prevents transfer of moisture via specially developed films and membranes with pores that are too small for water to pass through. Unable to be penetrated by water.

Water-Resistant - Repels water for a short time, but is not completely waterproof.

Water-Soluble - A substance that can be dissolved by or rinsed away with water without other agents.

Wax - Material made from a mixture of hydrocarbons or derivatives. Harder, less greasy and more brittle than its close relatives, fats, and is resistant to moisture, oxidization, and microbial attack.

Weak Acid - An acid that is partially dissociated in an aqueous (water) solution.

Wheat Complex - Ingredient extracted from wheat, believed to repair and renew skin and hair.

WHO - World Health Organization (WHO) is the United Nations agency for health and provides research, policy recommendations, and other resources for the world.

Whitehead - A non-inflammatory acne lesion that is a collection of sebum and keratin plugging the opening of hair follicle or pore. Also called a “closed comedome” because oil and skin cells block the opening of a hair follicle. Often painless, small, white bumps occurring around the nose, cheeks, or eyes. Whiteheads differ from blackheads because the follicle is closed, covered with a layer of skin and more likely to become infected. In blackheads the follicle remains open to the air. (See Acne, Blackhead, and Comedone)

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