CH. 7 HAIR & SCALP PROPERTIES

EUMELANIN

natural occurring pigment found in hair, skin, and eyes that provides darker coloring, contributing to shades of brown and black.

hair cuticle

the outermost layer of the hair shaft, consisting of overlapping cells. It protects the inner layers and contributes to the shine and smoothness of the hair.

COHNS elements

the five elements (carbon, hydrogen, oxygen, nitrogen, and sulfur) that make up the proteins in the hair structure.

trichology

the scientific study of hair and scalp health, focusing on growth, structure, and disorders.

polypeptide chain

also known as end bonds; chemical bond that joins amino acids to each other, end-to-end, to form a polypeptide chainthat makes up proteins in hair.

hydrogen bnond

weak physical cross link side bond that is easily broken by water or heat

telogen phase

also known as the resting phase: the final phase in the hair cycle that lasts until the fully grown hair is shedand new hair begins to grow in its place. During this phase, hair follicles remain inactive.

disulfied bond

strong chemical side bond that joins the sulfur atoms of two neighboring cysteine amino acids, forming a covalent link that provides strength and support to the hair structure.

lanthionine bond

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

hair porosity

the ability of hair to absorb and retain moisture, influenced by the condition of the hair cuticle.

melanin

tiny grains of pigment in the cortex that gives natural color to the hair

anagen phase

alsoknown as the growth phase of the hair cycle, during which the hair actively grows and can last several years.

vellus hair

fine, thin, and soft hair that covers most of the body and is often lighter in color than terminal hair.

hair shaft

the part of the hair that extends above the scalp, made of keratin, and is visible on the surface.

medulla

the innermost layer of hair, consisting of loose cells and air spaces, which contributes to the hair's overall structure and texture.

lanugo hair

fine, soft hair that develops on a fetus in the womb, typically shed before birth.

catagen phase

the transitional phase of the hair growth cycle, where hair stops growing and detaches from the follicle before entering the telogen phase.

whorl

a circular pattern of hair growth on the scalp, often seen as a spiral or swirl.

hair stream

the direction in which hair naturally grows, creating a distinct flow or pattern.

pheomelanin

a type of melanin that gives hair a yellow to red color, influencing the overall shade and appearance of hair.