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The branch of science that focuses on the hair, its diseases, and its care is called:
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trichology
The term "trichology" is derived from the Greek words trichos (hair) and ology (the study of). |
The hair is divided into two parts, the hair root and the:
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hair shaft
The hair shaft is the portion of the hair that projects beyond the skin. |
The hair root is made up of three main structures, the follicle, bulb, and:
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dermal papilla
The papilla is a small, cone-shaped elevation located at the base of the hair follicle that fits into the hair bulb. |
The tube-like depression in the skin that contains the hair root is the:
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follicle
The follicle grows downward from the epidermis into the dermis, where it surrounds the dermal papilla. |
The lower part of the hair root is the club-shaped:
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hair bulb
The lower part of the bulb fits over and covers the dermal papilla. |
The nutrients the hair needs for growth are supplied by the blood and nerve supply that are contained in the:
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dermal papilla
The dermal papilla is a small, cone-shaped elevation located at the bottom of the hair follicle that fits into the hair bulb. |
At the base of the follicle is a tiny involuntary muscle called the:
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arrector pili
Fear or cold cause this muscle to contract, making the hair stand up straight and resulting in "goose bumps." |
Sebum, the oily substance that lubricates the hair and skin, is secreted by the:
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sebaceous glands
The sebaceous glands are the oil glands of the skin, connected to the hair follicles. |
The hair shaft is made up of three layers; the cuticle, cortex, and:
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medulla
The medulla is the innermost layer, referred to as the pith or marrow of the hair shaft. |
The hair shaft is protected from penetration and damage by the:
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cuticle
The cuticle is the outermost layer of hair and consists of transparent, scale-like cells that overlap like shingles on a roof. |
The layer of hair that is generally only present in thick, coarse hair is the:
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medulla
It is quite common for the medulla to be lacking in other kinds of hair. |
Most of the total weight of the hair--about 90%--comes from the:
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cortex
The cortex is the middle layer of the hair and accounts for about 90% of its total weight. |
Swelling the hair raises the ________ and allows liquids to penetrate.
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cuticle
Swelling the hair raises the cuticle layer and opens the space between the scales, which allows liquids to penetrate. |
Oxidation haircolors, perm solutions, and chemical relaxers, in order to penetrate the cuticle, must have:
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an alkaline pH
These products all have a pH above 7.0, which raises the cuticle and allows penetration into the cortex. |
Permanent waving, chemical relaxing, and oxidation haircoloring cause changes that occur in the:
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cortex
The cortex is the middle layer of the hair and contains the structures affected by these procedures. |