milady chapter 7 - hair and scalp properties vocab

trichology

the Scientific study of hair and its diseases and care

hair root

The part of the hair located below the surface of the epidermis.

hair shaft

part of hair that is 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 bulb

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

dermal papilla

cone-shaped elevation found at the base of the bulb

hair cuticle

outermost layer of hair; formed from cells that resemble shingles on a roof; protects cortex

Cortex

fibrous protein layer of the hair; responsible for the strength, elasticity, and color of hair

medulla

innermost layer found in coarse hair and beard hair know as hairs pith or core absent in fine hair

Keratinization

Process by which newly formed cells in the hair bulb mature, fill with keratin, move upward, lose their nucleus, and die.

COHNS elements

the five elements- carbon, oxygen, hydrogen, nitrogen and sulfur- that make up human hair, skin, tissue, and nails.

side bonds

Bonds that cross-link the polypeptide chains together and are responsible for the extreme strength and elasticity of human hair account for about one third of hairs overall strength

hydrogen bond

A weak, physical, cross-link side bond that is easily broken by water or heat.

salt bond

A weak, physical, cross-link side bond between adjacent polypeptide chains that is broken by changes in PH

lanthionine bonds

The bonds created when disulfide bonds are broken by hydroxide chemical hair relaxers

Melanin

Tiny grains of pigment in the cortex that give natural color to the hair

Eumelanin

consists of brown and black pigment and is the predominant pigment in black and brunette hair

Pheomelanin

yellow to red pigment found in natural blonde to red shades of hair

Wave pattern

The amount of movement in the hair strand described as straight, wavy, curly or coily

hair texture

Thickness or diameter of the individual hair strand
fine,medium or coarse

hair density

Measures the number of individual strands on 1 square inch (2.5 cm) of the scalp.

hair porosity

refers to ability of the hair to absorb moisture

Hair elasticity

Ability of the hair to stretch and return to its original length without breaking

Hair stream

hair flowing in the same direction, resulting from follicles sloping in the same direction.

whorl

occurs when hair leaves the follicles at an angle; hair grows in a circular pattern on the crown of the head

cowlick

hair that grows straight up or at a different angle than the other hair; usually more 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 hair that appears on the body, often referred to as peach fuzz. It is typically less than one-third inch long (approximately one centimeter) and can appear anywhere on the skin apart from the palms, soles, and lips

terminal hair

Long, coarse, pigmented hair found on the scalp, legs, arms, and body

anagen phase

Also known as growth phase; phase during which new hair is produced.

catagen phase

brief transition period between the growth and resting phases of a hair follicle signals the end of the growth phase

telogen phase

Also known as resting phase; the final phase in the hair cycle that lasts until the fully grown hair is shed.