Hair and Scalp Properties

Trichology

The study of hair, including its diseases and care

Hair root

Located below the epidermis

Hair shaft

Also known as hair strand or hair fiber, is the nonliving portion of hair tag extends beyond the skin or scalp.

Projects above the epidermis

Hair follicle

Tube-like structure in the skin or scalp that surrounds the hair root and anchors the hair in the skin. Hair follicles not found on palms of hands or soles of feet

Hair bulb

Is located at the base of the follicle. It had a bulb shape and contains living cells that will form the hair strand

Dermal papilla (Hair Papilla)

Cone-shaped elevation at the base of the hair bulb. Contains blood vessels that supply nutrients that allow the hair to grow.

Arrector pili muscle

An involuntary muscle in the dermis that attaches to the hair follicle. Causes goosebumps

Sebaceous glands

Attached to the hair follicle, produce a substance called sebum, also known as oil. Sebum lubricates the hair and skin

Cosmetologists should have a thorough understanding of the properties of the hair and scalp because..

1. Analyzing the hair and scalp maintain their health and integrity

2. How hairstyling and chemical services alter hair can lead to safer, smarter services

3. Knowing difference between common and uncommon hair loss helps better recommend client hair loss treatments

Trichos

“Hair”

Ology

“The study of”

Integumentary System

Hair, Skin, Nails and glands

Parts of the Hair Shaft

1. Cuticle

2. Cortex

3. Medulla

Hair cuticle

The hairs outermost layer. It is formed from cells that overlap, similar to shingles on a roof.

Protects the cortex.

Healthy hair

Cuticle lies flat, but during chemical services, it will soften and swell, allowing the chemicals to penetrate the cortex

Cortex

The fibrous protein layer of the hair. Responsible for hair’s strength, elasticity, and color, and contributes to about 90% of hair’s weight.

Medulla

Also known as the hairs pith or core. Coarse hair has ____ but fine har doesn’t and Beard hair always contains ____.

Hair is compromised primarily of a protein called…

Keratin

Keratinization

1. New cells mature and fill up with keratin

2. Cells move upward, lose nucleous and die

3. Once hair strand emerges from scalp, hairs cells are dead and are completely keratinized

   
   

COHNS Elements

1. Carbon 51%

2. Oxygen 21%

3. Hydrogen 6%

4. Nitrogen 17%

5. Sulfur 5%

COHNS Elements are ALSO found in..

Skin and nails

Amino Acids

Link together end to end

Peptide bond

Strong chemical bond joins amino acids together

Polypeptide chain

A long chain formed from amino acids linked by peptide bonds

Exists in a spiral configuration called a helix

Side bonds

Account for about 1/3 of hairs overall strength, responsible for hairs strength and elasticity.

3 parts:

1. Hydrogen

2. Salt

3. Disulfide

Hydrogen bond

Weak Physical (side)

• Broken by water and heat

• reformed by drying or cooling

Salt Bond

Weak Physical (side)

• Broken by changes in pH (strong alkaline or acidic solutions)

• reformed by drying or cooling

Disulfide Bond

Strong Chemical (side)

• Broken by thio perms and thio relaxers and hydroxide relaxers

• reformed by oxidation with neutralizer and converters to lanthionine bonds

Peptide

Strong chemical (end)

• broken by chemical depliatories

• Not reformed; hair fissolves

Hydroxide chemical hair relaxers break disulfide bonds and convert them to _______

Lanthionine bonds

Melanin

Natural hair color pigment located within the cortex. Forms cells called melanocytes

Eumelanin

Brown and black pigment

Pheomelanin

Yellow to red pigment

Wave Pattern

Refers to the amount of movement or shape of the hair strand:

1. Straight

2. Wavy

3. Curly

4. Coily

Natural wave patterns

Result of genetics

Shape of the hair follicle determines the…

Shape of the hair strand

Straight hair

Round cross-section

Wavy or Curly hair

Oval cross-section

Very curly and coily hair

Elliptical-shaped cross section

The flatter the hair follicle is..

The curlier the hair will be

Wave Patterns

• varies throughout the head

• Can change during an individuals lifetime (hormones affect this)

• Are possible regardless of genetics

• Tends to be drier than straight hair and is accompanied by a drier scalp (due to shape of curled hair strand, the sebum produced by the body cannot reach ends of hair

Hair color

Refers to hair’s natural color

Haircolor

Artificial hair coloring products

Components of hair analysis

• texture

• Density

• Porosity

• Elasticity

• Growth patterns

• Dryness/oiliness of hair and scalp

Hair texture

Diameter of an individuals hair strand. Single strand needed to determine

• Fine (smallest diameter)

• Medium (average)

• Coarse (largest)

Hair Density

Measures the number of individual hair strands on 1 sq inch (2.5 sq cm) of scalp

• Low (thin)

• Medium

• High (thick)

Hair Density by Hair Color

Greatest to Least

• Blonde (140,000)

• Brown (110,000)

• Black (108,000)

• Red (80,000)

Hair porosity

Hair’s ability to absorb moisture. Determined by the cuticle layer’s condition and degree the “scales” of the cuticle are raised

Low porosity

Very healthy cuticle where the scales lie flat.

• more alkaline solution to raise the cuticle and permit uniform saturation and processing

• Feels smooth and cuticle is compact, dense, and hard

Average porosity

May have raised cuticle areas but the hair is still healthy.

• process as expected

• Feels slightly rough

High porosity

Result of previous overprocessing and raised cuticle

• less alkaline with lower pH prevent overprocessing and damage

• feels very rough, dry, or breaks

Porosity Test taken from different parts of the head

• Front hairline

• Temple

• Crown

• Nape

Hair elasticity

Hair elasticity is the hairs ability to stretch and return to its original length without breaking

• reflection of the strength of the side bonds in the cortex

• Wet hair - stretch between 30 to 50 %

• Dry hair - stretches about 20% of its length

Hair stream

• Hair flowing in the same direction is caused by follicles sloping in the same direction

• A natural part is caused by two hair streams flowing in opposite directions

Whorl

• occurs when hair leaves the follicles at an angle

• Hair grows in a circular pattern

• Sometimes there is more than one

Cowlick

• hair grows straight up or at a different angle than the other hair

• Usually more noticeable at crown but may be located anywhere on the head

Three types of body hair…

Lanugo, Vellus, and Terminal hair

Lanugo hair

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

Vellus

Is short, fine unpigmented body hair often referred to as peach fuzz, can appear anywhere on the skin apart from palms, soles, and lips

• less than 1/3 in long

• do not have sebaceous glands

• Helps evaporation of perspiration and body temperature regulation

Terminal hair

Long pigmented hair on the scalp and body

• coarser than Vellus hair

• May have a medulla

Anagram Phase

• Growth Phase

• New hair is produced

• New cells are produced in the follicle more quickly than any other cell in the body

• Average growth rate for healthy scalp hair is about 0.5 (1.25 cm) in per month

• Growth varies with age and gender

Cartagena phase

The brief transition period between the hair follicle’s growth and resting phases

• follicle canal shrinks and detaches from the dermal papilla