Hair and Scalp Properties Vocabulary

Vocabulary flashcards covering hair shaft structures, chemical composition, side bonds, hair analysis factors, growth patterns, and hair growth cycles.

Hair Shaft

The nonliving portion of hair that extends beyond the skin or scalp, consisting of the cuticle, cortex, and medulla.

Hair Cuticle

The hair's outermost layer, formed from overlapping cells similar to shingles on a roof, which protects the inner cortex.

Cortex

The fibrous protein layer of the hair responsible for its strength, elasticity, and color, which accounts for approximately $90\text{ percent}$ of the hair's weight.

Medulla

The hair's pith or core; present generally in coarse hair and always present in beard hair, but absent in fine hair.

COHNS Elements

The five major chemical elements that make up human hair: Carbon ($51\text{ percent}$), Oxygen ($21\text{ percent}$), Nitrogen ($17\text{ percent}$), Hydrogen ($6\text{ percent}$), and Sulfur ($5\text{ percent}$).

Keratinization

The process in which newly formed living cells in the hair bulb mature, fill with keratin, move upward, lose their nucleus, die, and emerge from the scalp as dead hair strands.

Peptide Bond

A very strong chemical end bond that joins amino acids together end to end to form a polypeptide chain.

Polypeptide Chain

A long chain of amino acids linked together by peptide bonds, existing in a spiral configuration called a helix.

Hydrogen Bond

A weak physical side bond resulting from the attraction of opposite charges that is easily broken by water or heat and reformed when drying or cooling.

Salt Bond

A weak physical side bond resulting from the attraction of opposite charges that is broken by changes in pH (strong alkaline or acidic solutions) and reformed by balancing pH.

Disulfide Bond

A strong chemical side bond joining sulfur atoms of two neighboring cysteine amino acids within polypeptide chains, broken by thio perms, thio relaxers, or hydroxide relaxers.

Lanthionine Bonds

Non-reformable bonds created when hydroxide chemical hair relaxers break disulfide bonds.

Melanin

The natural pigment located within the hair cortex, formed by cells called melanocytes, which determines natural hair color.

Eumelanin

The type of melanin consisting of brown and black pigment, which is the predominant pigment in black and brunette hair.

Pheomelanin

The type of melanin providing yellow to red pigment in natural blonde and red hair.

Wave Pattern

The amount of movement or shape of the hair strand, determined by the shape of the hair follicle and classified as straight, wavy, curly, or coily.

Hair Texture

The diameter of an individual hair strand, classified as fine (smallest diameter), medium (average diameter), or coarse (largest diameter).

Hair Density

The measure of the number of individual hair strands on $1\text{ square inch}$ ($2.5\text{ square centimeters}$) of scalp, classified as low (thin), medium, or high (thick).

Hair Porosity

The hair's ability to absorb moisture, determined by the condition of the cuticle layer and the degree to which cuticle scales are raised.

Hair Elasticity

The hair's ability to stretch and return to its original length without breaking, reflecting the strength of side bonds in the cortex.

Hair Stream

A growth pattern caused by hair follicles sloping in the same direction, resulting in hair flowing in the same direction.

Whorl

A growth pattern that occurs when hair leaves the follicles at an angle, causing hair to grow in a circular pattern.

Cowlick

A growth pattern where hair grows straight up or at a different angle than surrounding hair, usually noticeable at the crown.

Lanugo Hair

Short, fine hair that covers a fetus and generally sheds within a few weeks of birth.

Vellus Hair

Short, fine, unpigmented body hair ("peach fuzz") less than one-third inch ($1\text{ centimeter}$) long that lacks sebaceous glands and aids in body temperature regulation.

Terminal Hair

Long, pigmented hair found on the scalp and body that is coarser than vellus hair and may contain a medulla.

Anagen Phase

The growth phase of the hair cycle where new hair is produced, containing about $90\text{ percent}$ of scalp hair and lasting $2$ to $6$ years (up to $10$ years).

Catagen Phase

The brief $1$ to $2$ week transition period between hair growth and resting phases, where the follicle canal shrinks and detaches from the dermal papilla.

Telogen Phase

The resting phase of the hair growth cycle lasting $3$ to $6$ months, containing less than $10\text{ percent}$ of scalp hair before hair sheds or is pushed out by new growth.

Minoxidil and Finasteride

The only FDA-approved, scientifically proven treatments to help stop hair loss and possibly regrow hair.

Amino Acids

The building blocks of proteins, link together end to end like pop beads by strong, chemical peptide bonds (end bonds) to form the polypeptide chains that comprise proteins

Cysteine

amino acid with a sulfur (S) atom that joins together two peptide strands

Dermal papilla

cone-shaped elevation found at the base of the bulb

Hair Bulb

found at base of the follicle; has a bulb shape and contains living cells that will form the hair strand

Hair Follicle

tube-like structure in the skin or scalp that surrounds the hair root and anchors the hair in the skin

Hair Root

Part of the hair located below the surface of the epidermis

Medulla

innermost layer found in coarse hair and beard hair; known as hair’s pith or core; absent in fine hair

Side Bonds

bonds that cross-link polypeptide chains and are responsible for the extreme strength and elasticity of human hair; account for about one-third of hair’s overall strength

Trichology

scientific study of hair and its diseases and care

Myth: Shaving and cutting hair makes it grow back faster, darker, and coarser

This is a misconception as hair growth rate, pigmentation, and texture are determined by genetics, not shaving or cutting. Shaving does not affect the root structure of the hair.

Myth: Scalp massage increases hair growth

Scalp massage can stimulate blood microcirculation, which provides nutrients to the hair follicle. However, it has not been scientifically proven that stimulation or scalp massage increases hair growth.

Myth: Gray hair is coarser and more resistant than pigmented hair

Other than lack of pigment, gray hair is the same as pigmented hair

Oily Hair and Scalp

This condition is characterized by an excessive production of sebum from the sebaceous glands, leading to greasy hair and scalp. It can cause issues like dandruff and scalp irritation.

How to combat oily hair

Use shampoo that helps return the scalp to its own natual pH

Avoid products that are too harsh, as they can trigger additional oil production

thoroughly rinse hair after shampooing

Dry Hair and Scalp

Inactive sebaceous glands lead to lack of moisture and hydration in the hair and scalp, resulting in brittleness and flakiness.

How to combat dry hair

Use moisturizing shampoos and conditioners, incorporate deep conditioning treatments, and reduce heat styling to restore moisture. Avoid frequent shampooing, harsh soaps, detergent, and alcohol-heavy products.

Blonde Density

140,000 hairs

Brown Density

110,000

Black Density

108,000

Red Density

80,000

Average Hair Density

Approximately 2,200 hair per square inch, with a total of about 100,000 hairs on the scalp

Coarse Hair Chacteristics

Largest diameter, may require stronger chemicals than fine hair, higher tem. during thermal services, can be dry/frizzy

Medium Hair Chacteristics

Most common hair texure, standard to which other hair textures are compared, doesn’t present problems or concerns in styling

Fine Hair Charateristics

Smallest diameter, more fragile, can be easily weighed down, may process faster during chemical services, requires lower heat during thermal services

Components of Hair Analysis are:

texture, density, porosity, elasticity, dryness/oiliness of hair and scalp, and growth pattern.

What is the cross-section for straight hair

is round in shape, allowing the hair to lay flat and smooth. This structure contributes to its shine and sleek appearance.

What is the cross-section for wavy or curly hair

Oval to round cross-sectionwith an uneven surface, giving it volume and texture.

What is the cross-section for very curly hair

Elliptical cross-sectionthat results in tight curls and significant volume. This shape contributes to the hair's compact nature and can lead to dryness.

Hair Pigment

Natural hair color that’s determined by the type and amount of melanin

Difference between hair color and haircolor

Hair color means the natural hair color

Haircolor is the term for artificial haircoloring products