Chemical Makeup as it Pertains to Hair, Skin and Nails

Hair is a slender threadlike appendage, or extension of the skin. It is made of hard, keratinized protein. Keratin is a protein found in the human skin. It is located in the epidermis (the outer layer of skin, which is made of soft keratin that protects the body). There are two kinds of keratin: soft and hard. Hard keratin forms the chemical basis of hair. Hair is made up of approximately 51 percent carbon, 7 percent hydrogen, 18 percent nitrogen, 5 percent sulfur, and 19 percent oxygen. Hair is nourished (fed) by protein that comes from food. The protein is carried to the hair by blood vessels.

A molecule is the smallest possible unit of any compound. It is made up of two or more atoms chemically combined. These atoms are joined, or connected, by bonds. The building blocks of protein molecules are organic substances called amino acids. Healthy hair has 18 or more of these amino acids.

As a cosmetologist, you will be especially interested in two amino acids: cystine and tyrosine. Cystine is important for cold waving and chemical relaxing, while tyrosine is involved in hair coloring.

Hair is made beneath the scalp where amino acids form proteins. As it happens chemical reactions that produce peptide linkages take place. These peptide linkages are held together by cross-bonds. The hair has three types of cross-bonds: cyctine, hydrogen, and salt. When these cross-bonds are joined together in the hair they are called poly (many) peptide bonds. During hair-care services the polypeptide bonds are broken and re-formed by both physical and chemical actions. Hydrogen bonds are broken physically when the hair is stretched while it is still wet and wound around a roller. The bonds re-form as the hair dries in a curled position or shape.

Cystine bonds are broken chemically by applying reducing agents to the hair. Then the bonds are re-formed by oxidation. In cold waving, for example, the bonds are broken by ammonium thioglycolate (waving lotion) and reformed by hydrogen peroxide (the neutralizer).

The hair shaft is the dead portion of a hair that is above the skin. Starting from the inside and working out, the basic layers of the hair shaft are the medulla, cortex, and cuticle. The part of the hair below the skin is called the hair root.

The medulla is the innermost layer of the hair shaft. It may contain soft keratin. The medulla is the least important layer of the hair. Some hair such as lanugo hair (the short, soft hair found on some parts of the body, such as the arms) does not have a medulla.

The cortex, or middle layer, is the largest and possibly the most important layer of the hair. It makes up 75 percent of a single hair and contains the coloring pigment (melanin). Natural hair colors have one or a combination of the following pigments: yellow, red, brown, and black.

The cuticle is the outside layer of the hair: it consists of clear, horny cells that overlap to form the outer layer of the hair shaft. The density of the cuticle varies from 5 to 15 layers of cells, depending on a person’s race, Caucasians usually have fewer that 7 layers; Asians usually have from 7 to 10 layers; and African-Americans may have as many as 15 cuticle layers.

At this point, you have traced the hair backwards in a sense from the hair shaft to the follicle. The glands and the muscle are at the top of the follicle. Hair is made farther down, at the other end of the follicle.

The hair bulb is the bottom part of the follicle. The hair bulb almost completely surrounds a small, nipple-like projection called the papilla, which grows from the dermis (the layer of skin just below the epidermis). The papilla contains a nerve and the blood supply (one capillary-a very small vessel) needed to form hair and keep it growing.

In the middle and upper parts of the hair bulbs are melano-cytes that make melanin and cells for making hard keratin. Melanin gives hair its color. When the melanocytes cannot make melanin, a person’s hair turns gray.

The process of keratinization (changing keratin into hard protein) is slow. It occurs in stages, but when the hair comes out of the follicle it has been completely changed into hard protein.

The possibility of infection at the mouth of the follicle (right next to the skin, where the hair emerges) is a good example of why personal hygiene is important. There is a depression in the skin at the mouth of the follicle. This depression is a perfect place for bacteria, sebum, and dirt to collect. If this happens, it can cause either a minor infection or a serious disease.

As you know, hair can have different shapes and degrees of curliness. You often can see the four different categories by looking at cross sections of hair shafts under a microscope. A flat hair shaft is super-curly; a semi-oval one is curly; an oval one is wavy; and a round one is straight.

The angle at which the follicle approaches the surface of the skin can affect the shape of the hair. A follicle that is curved and parallel to the skin produces a super-curly hair shaft. A follicle that approaches the skin at a slight angle forms a wavy shaft. The angle of the follicle for a curly shaft is in between that for a super-curly and a wavy shaft. A follicle that is perpendicular to the surface of the skin produces a straight hair.

All human hair grows in cyclical periods that differ from one region of the body to another. Scalp hair, for example, grows for two to five years before it goes into a resting phase. Hair growth on the trunk, limbs and other areas occurs in periods of four to six months. Hair goes through three recognized cycles of growth: anagen, catagen and telogen.

The anagen stage is the growth period. The length of the anagen stage determines the length of the hair shaft. The anagen stage has two phases. During the first phase the hair bulb stretches itself out into the follicle. During the second period, hard keratin is synthesized in the follicle. Although the anagen stage normally lasts from 2 to 5 years, periods of 25 years have been recorded. In the anagen stage, scalp hair grows at a rate of about half an inch per month.

During the catagen stage, hair growth slows and club hairs form. Keratinization does not take place during this stage.

The telogen stage is a resting period that continues until the next anagen stage begins. Although scientists do not know exactly how long the telogen stage last they think it is short, three or four months.

The number of hairs on normal scalps varies according to hair color: 90,000 for red hair: 105,000 for black hair: 110,000 for brown hair: and 140,000 for blonde hair.

During the telogen stage, the hairs are removed easily by vigorous brushing. Under normal conditions, 85 to 95 percent of the terminal (coarse) scalp hairs are in the anagen stage: 1 percent is in the catagen stage: and from 4 to 14 percent are in the telogen stage.

You will probably see abnormal conditions (maybe even very serious disorders and diseases) of the hair. Although you will not-in fact, cannot-treat these diseases, you should be able to recognize them. Trichosis is any diseased condition of the hair.

Conditions of overgrowth:

Hypertrichosis-excessive growth of unwanted hair-is also called superfluous hair or hirsutism. Congenital hypertrichosis is considered hereditary.

Localized hypertrichosis takes two forms. Sometimes it appears as two or three hairs growing in a mole or as considerable growth over large areas of the body. Refer persons with hypertrichosis to a dermatologist. Electrolysis may be necessary to treat this condition, but should be done only on a doctor’s recommendation. If moles are not involved, it is all right to bleach or tweeze a few hairs on a small area of skin.

Classification of Hair Loss

Alopecia means hair loss. There are many kinds of alopecia and many reasons for it. The most familiar is probably alopecia of the scalp. There are two categories of alopecia of the scalp: (1) diffused (scattered) and (2) patchy. Patchy alopecia also comes in two varieties: one causes scars; the other does not. In the scarring variety, hair cannot grow because the papilla of the follicles has been destroyed.

There are five types of hair loss:

1. Male pattern hair loss.

2. Females pattern hair loss

3. Temporary hair loss in females.

4. Hair loss due to trauma caused by physical or chemical interference with natural growth.

5. Hair loss due to disorders of the body

Male pattern hair loss is a receding hairline caused by heredity, aging, or a decrease in hormones. Young clients should consult a dermatologist for preparations that may at least slow the hair loss.

Female pattern hair loss occurs in women over 50 as a result of a relative increase in the male hormone. There is no effective treatment, but maintenance of a healthy scalp is important.

Temporary hair loss in females can follow childbirth, nervous upset, or the use of anesthetics or may occur for no apparent reason. During pregnancy, hair growth increases, but after delivery, hair loss occurs until the body returns to its normal state.

Different kinds of trauma, both physical and chemical, can cause hair loss. Accident, injury, or infection (such as pneumonia) can cause hair loss because of the shock to the nervous system. Some chemicals used to treat diseases and conditions can also cause hair loss.

Some disorders of the body also can cause loss of hair. Diseases of the endocrine system of the body, such as an under active thyroid or pituitary gland, can lead to loss of hair. Some congenital (birth) defects can cause loss of nails as well as hair. Treatments for different kinds of cancer can also cause hair loss. When treatment stops, the hair grows back.

There are two types of patchy non-scarring hair loss:

Alopecia areata refers to an oval bald patch usually caused by bodily disorders. There may be one or several patches, but there is no scaling or infection. Alopecia areata usually affects the scalp, eyebrows, eyelashes, and beard, but it can occur in any area. In 6 to 12 months, the hair is usually (though not always) restored.

Tinea capitis (of the scalp) is characterized by broken-off hairs, scars and occasionally infection. This is a ringworm infection. The scales on the surface of the scalp are very white or gray. Do not serve a client with tinea of the scalp; advise the client to see a doctor.

Although they do not fall into the category of patchy non-scarring hair loss, four other types of alopecia exist. Total loss of scalp or body hair is called alopecia totalis; it is usually permanent. Its cause is unknown, but it may be linked to infections (teeth, prostate, sinuses, gallbladder, and so forth) and emotional problems. Heredity is also involved. Alopecia universal is a loss of hair all over the body. Alopecia senilis refers to loss of hair occurring in old age, and alopecia prematura refers to hair loss early in life.

Three types of patchy hair loss cause scars:

In many cases, you will be able to recognize hair diseases or disorders quickly and easily because you will notice that the client has lost a considerable amount of hair.

Pili is a general term that means pertaining to the hair. It appears in the names of many hair disorders.

Pili incarnati, or ingrown hair, occurs in individuals who have short, bristly, recurved hairs. This disorder affects facial areas that are shaved every day. The hair simply reenters the skin, irritates it and causes a pimple. This irritation can be complicated further if the disease does not stop when the hair is allowed to escape through an opening in the skin.

Trichoptilosis, or split ends, also known as fragilitas crinium (fragile hair shaft), is characterized by splitting along the length of the hair shafts. This is not a disease, and its cause is not known. Professional conditioning treatments should improve this disorder.

Prior to shampooing (or any other service), you must examine the scalp and hair to check for disease and analyze their condition so appropriate products can be selected. If a communicable disease is present, do not service the client. Do not shampoo the hair vigorously before giving a permanent wave, chemical relaxer, or other chemical service. In most cases, a shampoo before chemical services is performed with very gentle manipulations.

As a cosmetologist, you will be concerned about recognizing communicable diseases. A congenital disease is a disorder that has existed since birth. (A person born with a heart condition has a congenital disease.) A chronic disease, such as emphysema is a long-term or recurring disorder. A short-term condition, such as common cold, is called an acute disease.

In examining the scalp and hair, you should watch for skin diseases (infections of the skin). Probably the most common skin disorder observed in the beauty salon is dandruff. It is characterized by an excessive number of small or large white flat scales shed from the outermost layer of the skin of the scalp.

The medical term for dandruff is pityriasis. There are two forms of pityriasis. Pityriasis capitis simplex is characterized by dry, flaky, white scales and may be treated by using a nonprescription medicated shampoo.

Yellow oily or waxy scales located close to the scalp characterize pityriasis steatoides. Sebaceous glands in the scalp produce a lubricating substance called sebum. If the sebaceous glands become overactive when dandruff is on a person’s scalp, the scales stick together and become attached to the scalp and hair. Ordinary shampoos will not remove these scales, flakes and oil deposits. This condition may require a medicated shampoo.

Psoriasis is a skin disease that can be chronic or acute. It is characterized by inflamed (red) patches and overlapping yellow or white scales. It is not contagious, and although the crust will bleed if disturbed, clients with psoriasis may receive cold waves and use hair colors.

Herpes simplex is a viral infection (from a virus) characterized by inflammation of the skin and mucous membranes, especially those of the face and lips. Such inflammations are called cold sores. Exactly how this condition develops is not known, but it usually clears up in 6 to 10 days. It is a contagious condition, so facials and makeup applications are not recommended.

Pediculosis is an animal parasitic condition. (A parasite is an organism or microorganism that lives on another organism.) Pediculosis involves head lice that lay their eggs on the scalp and hair shafts. Because of improved personal hygiene in the United States, head lice were not a common problem during the last few decades. Since pediculosis is contagious, a client with this condition cannot be served in the school or salon. Effective treatment, including a medicated shampoo prescribed by a doctor or simply purchased over-the-counter at a pharmacy, can eliminate the condition in three or four days.

Scabies is another animal parasitic condition. It is an infestation of itch mites, which burrow into the scalp and cause irritation, leading to the scratching of the scalp. Scabies is very contagious. Refuse service to a person with this condition and refer him or her to a doctor.

Tinea, a skin infection caused by a fungus (vegetable parasite), is very contagious. This condition, which is commonly called ringworm, appears as circular inflamed areas of little blisters. A person with tinea cannot be served and should be advised to see a doctor.

Seborrhea is a disorder of the sebaceous glands, which causes an excessively oily scalp and hair. Hyperactivity (over activity) of the sebaceous glands causes this excessive secretion of sebum, which is transferred from the scalp to the hair. Using a medicated shampoo for oily hair can control seborrhea. Daily shampoos may be needed.

Asteatosis is caused by hypoactivity (under activity) of the sebaceous glands. The glands product too little sebum which results in dry, scaly skin and/or hair that lacks luster. This is an unusual condition that is seldom seen in the salon.

A steatoma, or wen, is a subcutaneous (beneath the skin) cyst occurring when the duct from the sebaceous gland to a hair follicle becomes clogged or blocked. Sebum accumulates and hardens beneath the skin until the duct is open again. This condition is not considered contagious.

Acne is an eruptive skin disease caused by inflammation (irritation) of the sebaceous glands. It usually appears on the face, chest, and back. A dermatologist can control the condition. Clients having acne can be served in the salon and school.

Comedones, also called blackheads, occur when the skin is not cleansed properly and regularly. Sebum hardens around a speck of dirt or dust, clogging a pore and creating a slightly raised area.

Milia, also called whiteheads, are cysts that contain sebum trapped in a sebaceous duct.

Miliaria rubra is an acute irritation below the top layer of skin. It is an inflammation of the sudoriferous (sweat) glands. Commonly called prickly heat, this disorder usually occurs during hot weather. It is not communicable.

Since these services are performed directly on the skin of the clients, it is important that they be done safely. In order to do that, the practitioner (esthetician or cosmetologist) must have a thorough understanding of the histology (microscopic study) of the skin, including its structure and functions.

The practitioner should be familiar with some of the more common disorders and diseases of the skin. Your job is knowing when you cannot safely give a service to a client and must refer the client to a physician or dermatologist.

The skin is the largest and one of the most efficient organs of the human body. It grows, reacts to sensation, and constantly renews itself. The skin is divided into three layers:

Epidermis                Corium (Dermis)           Subcutaneous tissue

The epidermis is the thinnest and outermost layer of the skin. It is about as thick as this page. Although you can only see these skin cells through a microscope, they are very active.

The corium or dermis is the true skin. It is 20 to 30 times thicker than the epidermis and rests upon a thick pad of fatty or adipose subcutaneous tissue. This subcutaneous tissue below the corium is the third layer of the skin. It serves as a shock absorber and heat insulator for the body.

The protein, collagen, is produced in the dermis or corium layer of the skin. This protein gives skin its elasticity and prevents the wrinkling of the skin associated with aging and overexposure to harmful ultraviolet light from the sun or tanning beds.

Recently, dermatologists have discovered that a drug called Retin-A is very effective in preventing wrinkling of the skin; it also reduces wrinkles and stretch marks that have already appeared. Originally Retin-A was prescribed to treat acne, and its initial approval by the Food and Drug Administration (FDA) was for that purpose. Now, however although it is still used to treat acne, it is used against wrinkles as well. Retin-A seems to slow down the aging process and normalize skin functions by increasing the amount of collagen in the upper part of the dermis. In addition, Retin-A makes the skin smoother by reducing the production of melanin (the coloring pigment in the skin). Studies have shown that the drug can be effective in reducing wrinkling around the corners of the eyes (known as crows’ feet) and that it reduces the formation of dark liver spots on the skin. Although Retin-A is used mainly on the face some patients have used it successfully on their arms and legs as well.

Retin-A makes the skin much more sensitive to ultraviolet light from the sun and from tanning lamps. Thus, the skin will burn much more easily. Therefore, anyone who is being treated with this drug must use sun-blocking product to protect the skin.

In general, the skin serves as a barrier between the organs inside the body and the rest of the world. Specifically, the skin has five important functions:

Protection. It protects the body from physical or chemical injury and from bacteria. Thus, it is both a shock absorber and a barrier against bacteria and viruses.

Heat regulation. It keeps the body’s internal temperature at 98.6 F (37 C). Blood flows in the vessels to keep the body warm, while the sweat glands serve as the cooling system.

Sensation. The body feels heat, cold, pain, and touch through a network of nerve endings that are located all over the surface of the skin.

Secretion. Perspiration secreted by the sweat glands is practically the only waste removed by the skin.

Absorption Most liquids will not pass through the skin unless the layers have actually been destroyed, punctured, or penetrated. Scientists believe that only small quantities of substances enter the skin through the sweat ducts.

Glands are groups of cells that take certain substances from the blood, make new substances out of them, and then release the new substances, which are called secretions. Skin glands fall into two general categories-sebaceous and sudoriferous.

The sebaceous glands are present all over the body except in the palms of the hands and the soles of the feet. They secrete an oily fluid called sebum through a duct to a follicle that may contain a hair. The sebum is actually material from cells that have broken down. When a sebaceous gland secretes sebum through its duct, the entire gland falls apart and is pushed out through the duct. Sebaceous glands are much larger and more numerous on the scalp and face than elsewhere on the body.

The oily sebum covers the skin with a film that helps fight bacteria and fungus. It also slows the evaporation of moisture (water) from the skin and protects against bacteria. The amount of sebum secreted depends on several factors. Some people have small, underdeveloped sebaceous glands, while others have numerous large glands that cause greasy, oily skin.

Introduction to Nails:

This section presents important information about human fingernails and toenails, including their shapes, growth, structure, disorders, and diseases. Knowing this information will help you give manicures and pedicures successfully. You will need to be able to recognize certain nail disorders and diseases so that you can answer clients’ questions about them and also so that you can protect yourself from performing services on clients who have a highly contagious disease. If you give a service to a client who has a contagious disease, you may become affected with the disease yourself and spread it to other clients visiting the salon.

Although nail shapes may very, four shapes are generally recognized: square, round, oval, and pointed. The oval shape is usually the most complimentary, but current fashions, finger shape, and the needs of the client should be considered.

The fingernail is an appendage of the skin. It includes the nail plate and the tissues that surround it.

The nail plate (nail body) is the visible (almost clear) hard keratin portion on the top of the finger. The tissue directly under the nail plate is called the nail bed. A healthy nail looks pink because the blood that flows to the nail bed can be seen through the nail plate.

The free edge of the nail is that part that extends beyond the end of the fingertip and can be seen from both above and below the hand.

The nail is surrounded by the cuticle, eponychium, nail wall, nail groove, nail mantle, hyponychium, and perionychium. Each of these structures is described below:

The cuticle is a thin semicircular piece of skin that overlaps that nail.

The eponychium is the inside point where the nail enters the skin.

The nail wall is a semicircular fold of skin that overlaps the nail plate on either side and extends to the first knuckle.

The nail groove is the channel (slit) on each side of the nail plate. This is where the nail moves when it grows.

The nail root is beneath the skin at the base of the nail in a deep fold of skin called the nail mantle.

The hyponychium is the skin located directly beneath the nail’s free edge.

The peroinychium is the skin that surrounds the entire nail.

The matrix is the inner part of the nail. It affects the nail’s shape, size, regeneration, and growth. The matrix contains the lymph, blood vessels, and nerves that help the nail grow. Keratin grows and hardens in the matrix. This process produces the nail body. A bacterial infection in which pus is produced in the matrix is called onychia.

The light arc at the base of the nail is called the lunula. It has a half-moon shape. This light color results from an air pocket between the nail plate and the nail bed at the base of the nail.

If the matrix is injured, the nail’s growth and shape can be distorted. Unlike hair, nails grow continuously at the rate of 1/8 inch per month. (They grow faster in summer than in winter.) If a nail is lost or removed, it will take about 3-4 months to restore a fingernail and 9 months for a toenail. The middle fingernail grows fastest, the thumbnail slowest.

In general, you can recognize nail diseases by inflammation of the skin surrounding the nail, soreness causing extreme discomfort, and other signs of infection.

The cosmetologist or nail specialist may encounter some of the following diseases:

Onychomycosis, also known as tinea unguis, is ringworm of the finger or toenails. In this condition, a vegetable fungus (parasite) disturbs the nail growth. Onychomycosis is not very common, but it is very contagious. The condition is characterized by thickening and deformity and finally loss of the nail.

Cause: Heredity can be a factor but this disease usually results from a nail injury coupled with an invasion by a fungus.

Prognosis: The nail usually requires 3 months to grow back if a doctor treats it. Although the condition is resistant to treatment, competent dermatologists treat it with success.

Treatment: Tell the client to obtain a doctor’s advice immediately.

Tinea of the hands affects the skin rather that the nails, but you should be aware of it. It is a rare infection that is sometimes called the one-hand-two-foot disease because it affects only one hand but both feet. Its acute (short-term) form is characterized by blisters at the edge of inflamed areas on the palm and fingers. In its chronic (long-term) state, it can be identified by dry, scaly lesions, which usually occur in one large patch instead of several areas.

Cause: It is a fungus infection.

Prognosis: It is resistant to treatment.

Treatment: Tell client to see a doctor for treatment.

Onychocryptosis is the technical term for an ingrown nail. It is characterized by the lateral growth of the nail plate into the edge of the nail groove. Usually it occurs in the big toe, but it may also occur in the other toenails and fingernails.

Cause: Improperly fitting (tight) shoes and incorrect trimming can cause the condition.

Treatment: It may be remedied by trimming the nail in a semi-lunar (crescent-shaped) manner so that the corner of the nail is raised above the skin surface. In cases of extreme discomfort, a doctor should be consulted for surgical relief and /or advice about bacterial infection.

Onychogryposis, also called claw nails, involves marked thickening of the nail. The nail plate becomes elongated and twisted (curved).

Cause: The condition results from trauma (shock): other causes are unknown.

Prognosis and treatment: Tell the client to get a doctor’s advice.

Onycholysis involves a spontaneous separation of the nail plate from the nail bed, without actual shedding.

Cause: Local or general infections and treatment with certain types of antibiotic drugs may cause the condition.

Prognosis and treatment: Tell the client to consult a doctor.

Paronychia or felon is a bacterial infection of the tissue around the nail. It is characterized by pain, redness, and swelling of the skin around the nail plate, without nail loss. This condition is very contagious, so it is not treated in the school or salon.

Cause: People who have their hands in water for long periods of time may develop this condition. Dishwashers and cosmetologists are particularly likely to have it.

Prognosis: This condition usually responds well when treated by a doctor.

Treatment: Tell the client to ask a doctor for advice.

Eggshell nails or hapalonychia involves very thin, fragile nails that are white in color. These nails split and break easily. A defect in the nail matrix causes this condition.

Cause: This condition is rare, but it can result from aging and/or the use of acetone or hydroxide solutions in manicuring.

Prognosis and treatment: Using nail hardeners or polish (enamel) strengthens these nails and prevents splitting. 

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