Ch. 6, 7, and 8 Nail Diseases and Disorders, Hair and Scalp Properties, and Hair and Scalp Diseases and Disorders

Beau's lines

depressions running across the nail plate's cells width due to a slowing production of matrix

bruised nail bed

dark purplish spots, usually due to a small nail bed injury

discolored nail

nail that has turned a variety of colors; may indicate surface staining, a systemic disorder, or poor blood circulation

eggshell nail

noticeably thin, white nail plate that is more flexible than usual; usually caused by diet, heredity, internal disease, medication, or overfiling with an abrasive

hangnail

damaged skin around the nail plate (often on the eponychium) becomes split or torn

infected finger

finger with visible redness, pain, swelling, broken skin, or pus

leukonychia

whitish discoloration found inside the nail plate, usually caused by injury to the nail matrix

melanonychia

significant darkening of the fingernails or toenails caused by increased pigment cells (melanocytes); may be seen as a black band under or within the nail plate, extending from the base to the free edge

nail disorder

an unhealthy nail condition that is hereditary or caused by injury or disease of the nail unit

nail melanoma

Also known as subungual melanoma; a rare and serious type of skin cancer that begins in the nail matrix. It is more prevalent in the nails of your thumbs and big toes and usually affects one nail at a time. Sometimes it can look like other conditions that affect the nail bed, such as a bruise. If untreated it can metastasize or spread to other parts of your body.

nail psoriasis

nail surface pitting, roughness, onycholysis, and bed discolorations randomly or evenly spaced; nail plate may appear as if it has been filed with a coarse abrasive, or the free edge may be ragged, or both

nail pterygium

irregular stretching of the eponychium or hyponychium around the nail plate; usually from serious injury or an allergic skin reaction

onychia

inflammation of the nail matrix followed by shedding of the natural nail caused by infection or injury

onychocryptosis

also known as ingrown nail; nail grows into the living tissue around the nail

onycholysis

separation of the nail plate and bed, often due to injury or allergic reactions

onychomadesis

separation and falling off of a nail plate from the nail bed; caused by infection, matrix injury, systemic illness, or medical procedure

onychomycosis

nail plate fungal infection, consisting of whitish patches that can be scraped off the nail's surface or long whitish or pale yellowish streaks within the nail plate

onychophagy

also known as bitten nails; result of a habit of chewing the nail or chewing the hardened skin surrounding the nail

onychorrhexis

irregular split or brittle nails appearing as nail plate surface roughness; potentially caused by heredity, matrix injury, excessive exposure to cuticle removers, harsh cleaning agents, or aggressive filing techniques

onychosis

any deformity or disease of the natural nails

paronychia

bacterial inflammation of the tissues surrounding the nail; redness, pus, and swelling are usually present

pincer nail

also known as trumpet nail; a form of dramatically increased nail curvature of the free edge, whereby the nail can curl upon itself or may be deformed only on one sidewall

plicatured nail

also known as folded nail; a type of highly curved nail plate usually caused by injury to the matrix, but may be inherited

Pseudomonas aeruginosa

rapidly growing and contagious bacteria that can cause infection; seen in the early stages as a yellow-green spot that becomes darker in its advanced stage, changing from yellow to green to brown to black.

pyogenic granuloma

severe inflammation of the nail in which a lump of red tissue grows up from the nail bed to the nail plate.

ridged nail

vertical lines running the length of the natural nail plate, usually the result of aging.

splinter hemorrhage

damage to the capillaries under the nail, giving the appearance of a lengthwise small splinter underneath the nail plate; caused by physical trauma or nail bed injury.

tinea pedis

also known as athlete's foot; medical term for fungal infection of the feet; often seen as red patches or scaling of the skin on the bottom of feet and/or between the toes.

amino acids

Form the building blocks of protein; link together end to end like pop beads by strong, chemical peptide bonds (end bonds) to form the polypeptide chains that comprise proteins.

anagen phase

Also known as the growth phase; hair 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.

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.

cysteine

Amino acid with a sulfur ($S$) atom that joins together two peptide strands.

dermal papilla

Cone-shaped elevation found at the base of the bulb (plural: dermal papillae).

disulfide bond

Strong chemical side bond that joins the sulfur atoms of two neighboring cysteine amino acids to create one cysteine, which joins together two polypeptide strands like rungs on a ladder.

eumelanin

Consists of brown and black pigment and is the predominant pigment in black and brunette hair.

hair bulb

Found at 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 on a roof; protects cortex.

hair density

Measures the number of individual hair strands on $1\, \text{square inch}$ ($2.5\, \text{square centimeters}$) 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 shaft

Part of the hair that projects above 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 individual hair strand.

hydrogen bond

Weak physical cross-link side bond that is easily broken by water or heat.

lanthionine bonds

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

lango hair

Short, fine hair that covers a fetus and generally sheds within a few weeks of birth.

medulla

Innermost layer found in coarse hair and beard hair; known as hair's pith or core; absent in fine hair.

melanin

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

peptide bond

Also known as an end bond; chemical bond that joins amino acids to each other, end-to-end, to form a polypeptide chain.

pheomelanin

Yellow to red pigment found in natural blonde to red shades of hair.

polypeptide chain

Long chain of amino acids linked by peptide bonds.

salt bond

Weak physical cross-link side bond between adjacent polypeptide chains that is broken by changes in pH.

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 hair’s overall strength.

telogen phase

Also known as resting phase; the final phase in 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.

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; typically less than one inch long (approximately one centimeter) and can appear anywhere on the skin apart from the palms, soles, and lips.

wave pattern

Amount of movement or shape of the hair strand; described as straight, wavy, curly, or coily.

whorl

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

alopecia

partial or complete hair loss from where it typically grows

alopecia areata

autoimmune disorder that causes the affected hair follicles to be attacked by the immune system; usually begins with one or more small, round, smooth bald patches on the scalp

alopecia totalis

total loss of all terminal scalp hair

alopecia universalis

loss of terminal hair on the body and scalp

androgenic alopecia

also known as androgenetic alopecia; hair loss characterized by miniaturization of terminal hair and a shortened anagen phase; it can affect anyone and is caused by genetics, age, or hormonal changes

canities

technical term for gray or white hair; results from the loss of the hair's natural melanin pigment

carbuncles

inflammation of the subcutaneous tissue caused by staphylococci; a cluster of furuncles

folliculitis

inflammation or infection of the hair follicles

fragilitas crinium

technical term for brittle hair

furuncle

boil; acute, localized bacterial infection of the tissue surrounding a hair follicle

hirsuties

growth of terminal hair on a woman's body in an area that would not typically have terminal hair; often found on upper lip, chin, cheeks and chest

hypertrichosis

condition of hair growth where the hair grows longer or thicker than usual

malassezia

naturally occurring fungus that is present on all human skin; fungus that causes visibly shed skin cells, or dandruff, that can sit on the scalp and create dryness, itchiness, and discomfort

melanin

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

monilethrix

technical term for beaded hair

pediculosis capitis

infestation of the hair and scalp with head lice

pityriasis

technical term for dandruff; characterized by excessive production and shedding of skin cells

pityriasis capitis simplex

technical term for classic dandruff; characterized by scalp irritation, large flakes, and itchy scalp

pityriasis steatoides

severe case of dandruff characterized by an accumulation of greasy or waxy scales mixed with sebum that stick to the scalp in crusts

postpartum alopecia

temporary hair loss experienced after the conclusion of pregnancy

ringed hair

variety of canities characterized by alternating bands of gray and pigmented hair throughout the length of the hair strand

scabies

highly contagious condition caused by mites called Sarcoptes scabiei that lay eggs inside the skin

scutula

dry, sulfur-yellow crusts on the scalp in tinea favosa or tinea flava; has distinctive odor

tinea

ringworm; contagious condition caused by fungal infection; characterized by itching, scales, and—sometimes—painful lesions

tinea favosa

also known as tinea favus or honeycomb ringworm; fungal infection characterized by dry, sulfur-yellow crusts on the scalp called scutula

trichoptilosis

split ends

trichorrhexis nodosa

knotted hair; characterized by brittleness and the formation of nodular swellings along the hair shaft