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milady book part 2
hair and scalp properties vocab
Term | Definition |
---|---|
arrector pili muscle | an involuntary muscle in the dermis that attaches to the hair follicle. When it contracts, the hair strand stands up, causing goosebumps |
sebum | also known as oil sebum lubricates the hair and skin |
sebaceous glands | are attracted to the hair follicle. They produce a substance called sebum also known as oil |
keratinization | process by which newly formed cells in the hair bulb mature, fill with keratin, move upward, lose their nucleus and die |
anagen phase | also known as the growth phase; hair phase during which new hair is produced |
catagen phase | brief transiting period between growth and resting phases of a hair follicle; signals the end of the growth phase |
COHNS elements | five elements- carbon, oxygen, hydrogen, nitrogen and sulfur- that make up human hair, skin, tissue and nails |
cortex | fibrous protein layer of the hair; responsible for the strength, elasticity and color of hair |
cowlick | hair that grows straight up or at a different angle than the other hair; usually more noticeable at the crown |
dermal papilla | cone-shaped elevation found at the base of the bulb |
eumelanin | consists of brown and black pigment and is the predominant pigment in black and brunette hair |
hair bulb | found at the base of the follicle; has a bulb shape and contains living cells that will form the hair strand |
hair cuticle | outermost layer of hair; formed from cells that resemble shingles and a roof; protects cortex |
hair density | measures the number individual hair strands on 1 square inch of scalp |
hair elasticity | ability of the hair to stretch and return to its original length without breaking |
hair follicle | tube-like structure in the skin or scalp that surrounds the hair root and anchors the hair in the skin |
hair porosity | refers to ability of the hair to absorb moisture |
hair root | part of the hair located below the surface of the epidermis |
hair stream | hair flowing in the same direction, resulting from follicles sloping in the same direction |
hair texture | thickness or diameter of an individuals hair strand |
hydrogen bond | weak physical cross-link side bond that is easily broken by water or heat |
lanugo hair | short, fine hair that covers a fetus and generally sheds within a few weeks of birth |
lanthionine bonds | bonds created when disulfide bonds are broken by hydroxide chemical hair relaxers |
medulla | innermost layer found in coarse hair and beard hair; known as hairs pith or core; absent in fine hair |
melanin | tiny grains of pigment in the cortex that give natural color to the hair |
pheomelanin | yellow to red pigment found in natural blonde to red shades of hair |
keratin | newly formed cells mature and fill up with a fibrous protein |
trichology | scientific study of hair and its diseases and care |
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 and can appear anywhere on the skin apart from the palms, soles and lips |
telogen phase | also known as resting phase; the final phase inn the hair cycle that lasts until the fully grown hair is shed |
terminal hair | long coarse pigmented hair found on the scalp, legs, arms and body |
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 hairs overall strength |
salt bond | weak physical cross-link side bond between adjacent polypeptide chains that is broken by changed in pH |