Trichology and Hair Structure Practice Flashcards

Comprehensive vocabulary flashcards covering the biological structure, chemical composition, growth cycles, and various disorders of human hair based on the lecture notes.

Trichology

The scientific study of hair, its diseases, and care.

Hair

A keratinous threadlike filament growing out of the epidermis.

Integumentary system

Consists of the skin and its accessory organs such as oil and sweat glands, sensory receptors, hair, and nails.

Epidermis

The outermost and thinnest layer of the skin.

Stratum corneum

The layer of skin made up of keratin, a fibrous protein that is the principal component of hair and nails.

Dermis

The skin's underlying or inner layer containing blood vessels, nerves, glands, and hair follicles.

Hair root

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

Hair shaft

The portion of the hair that projects above the epidermis.

Hair follicle

The tube-like depression or pocket in the skin or scalp that contains the hair root.

Hair bulb

The lowest part of a hair strand; a thickened, club-shaped structure that forms the lower part of the root and covers the dermal papilla.

Dermal papilla

Small, cone-shaped elevations located at the base of the hair follicle containing the blood and nerve supply for nutrients.

Arrector pili muscle

Minute, involuntary muscle fibers in the skin inserted at the base of the hair follicle that cause goosebumps when contracted.

Sebaceous glands

Oil glands connected to the hair follicles that secrete sebum.

Sebum

An oily substance secreted by the sebaceous glands that lubricates the hair and skin.

Hair Cuticle

The outermost layer of the hair consisting of a single, overlapping layer of transparent, scale-like cells.

Cortex

The middle layer of the hair; a fibrous protein core formed by elongated cells containing melanin pigment and providing elasticity.

Medulla

The innermost layer of the hair, which may be absent in very fine or naturally blonde hair.

Keratinization

The process by which living cells form in the follicle and mature as they journey upward through the hair follicle.

COHNS elements

The major elements making up human hair: Carbon ($51\%$), Oxygen ($21\%$), Hydrogen ($6\%$), Nitrogen ($17\%$), and Sulfur ($5\%$).

Amino acids

Units that are joined together end-to-end like pop beads to make up proteins.

Peptide bond

Also known as an end bond; a strong chemical bond that joins amino acids.

Polypeptide chain

A long chain of amino acids linked together by peptide bonds.

Helix

The spiral shape of a coiled protein created when polypeptide chains intertwine.

Hydrogen bond

A weak, physical, cross-link side bond that is easily broken by water or heat and reforms when hair dries.

Salt bond

A weak, physical, cross-link side bond between adjacent polypeptide chains that depends on pH and is broken by strong alkaline or acidic solutions.

Disulfide bond

A strong, chemical side bond that joins the sulfur atoms of two neighboring cysteine amino acids to create one cystine.

Melanin

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

Eumelanin

A type of melanin that provides dark brown and black color to hair.

Pheomelanin

A type of melanin that provides natural hair colors from red and ginger to yellow and blond tones.

Wave pattern

Refers to the shape of the hair strand, described as straight, wavy, curly, or extremely curly.

Vellus hair

Also known as lanugo hair; short, fine, downy, unpigmented hair found on most of the body except palms and soles.

Terminal hair

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

Anagen phase

The growth phase where new hair is produced; about $90\%$ of scalp hair is in this phase at one time.

Catagen phase

The brief transition period between the growth and resting phases, where the follicle canal shrinks and detaches from the dermal papilla.

Telogen phase

The final resting phase of the hair cycle that lasts until the fully grown hair is shed.

Alopecia

The technical term for abnormal hair loss.

Androgenic alopecia

Hair loss characterized by miniaturization of terminal hair that is converted into vellus hair; often linked to genetics, age, or hormones.

Alopecia Areata

An autoimmune disorder that cause the immune system to attack hair follicles, resulting in small, round, smooth bald patches.

Alopecia Totalis

Total scalp hair loss.

Alopecia Universalis

Total body hair loss.

Postpartum alopecia

Temporary hair loss experienced at the end of a pregnancy.

Minoxidil

A topical medication put on the scalp twice a day proven to stimulate hair growth.

Finasteride

An oral medication for men only proven to stimulate hair growth, but carries risks of birth defects if used by women.

Canities

The technical term for grey hair, resulting from the loss of natural melanin.

Hypertrichosis

Also known as hirsuties; a condition of abnormal terminal hair growth in areas that normally only grow vellus hair.

Trichoptilosis

The technical term for split hair ends.

Trichorrhexis Nodosa

The technical term for knotted hair, characterized by brittleness and nodular swellings along the hair shaft.

Monilethrix

The technical term for beaded hair; the hair breaks easily between the beads.

Fragilitas Crinium

The technical term for brittle hair.

Pityriasis

The technical term for dandruff, characterized by excessive production and accumulation of skin cells.

Malassezia

A naturally occurring fungus present on all human skin that causes dandruff symptoms when it grows out of control.

Pityriasis Capitis Simplex

Technical term for classic dandruff characterized by a dry, itchy scalp and large flakes.

Pityriasis Steatoides

A severe case of dandruff involving an accumulation of greasy or waxy scales mixed with sebum.

Tinea

The technical term for ringworm; caused by a fungal organism and characterized by itching and circular lesions.

Tinea Favosa

Characterized by dry, sulfur-yellow, cup-like crusts on the scalp called scutula.

Scutula

Dry, sulfur-yellow, cup-like crusts on the scalp associated with Tinea Favosa.

Scabies

A highly contagious skin disease caused by a parasite called a mite that burrows under the skin.

Pediculosis Capitis

A contagious condition caused by head lice infesting the hair and scalp.

Furuncle

The technical term for a boil; an acute localized infection of the hair follicle.

Carbuncle

A cluster of boils caused by a bacterial infection, larger than a furuncle.

Folliculitis

Also known as barbers itch; an infection of the hair follicles often seen as small white-headed pimples.