21.4: Key Terms

acne vulgaris

a common inflammatory skin reaction caused by bacteria, dead skin cells, or dried sebum that clogs hair follicles and prevents sebum from passing up through the pores

angioedema

swelling of the face, lips, throat, or airways

apocrine gland

correlates with the hair follicles present in the perineum, axillae, and areolae of the breasts

arrector pili muscle

triggers hair follicle on the body to flex causing the hair to rise up

basal cell carcinoma

the most common skin cancer that is generally found on the head or neck; it may be serious but is not usually fatal

blackhead

flesh-colored, small bump with a dark center

bulla

large blister

bullous impetigo

type of impetigo that has large, flaccid bullae on the skin that rupture and leave a thin brown crust

carbuncle

skin abscess that connects to others below the surface of the skin to form clusters, often forming when one of more hair follicles become infected

cellulitis

localized infection and inflammation of the skin and tissues that are immediately beneath the skin

comedone extraction

use of a comedone extractor by a healthcare professional to remove blackheads and whiteheads by incising the pore and then using gentle pressure around the pore opening with a wire loop

cystic acne

lesions that are usually large, red, painful, and pus-filled nodules that merge under the skin and often leave scars

defensin

has antimicrobial and/or cytotoxic properties and is part of the body’s first immune defense

dermatosis papulose nigra

small dark or skin-colored bumps on the face, neck, and upper torso, common in people with darker skin colors

dermis

the layer of skin below the epidermis connected to the epidermis by dermal papillae

disseminated zoster

herpes zoster rash that affects three or more dermatomes

eccrine gland

is located over the skin entirely, secretes sweat, and aids in thermoregulation

ecthyma

(deep impetigo) a skin infection that occurs deep inside the skin characterized by shallow, small ulcers that look punched-out and may contain pus

eczema

(atopic dermatitis) rash characterized by itchy, chronic inflammation of the upper skin layers and is associated with a heightened immune response

emollient

ingredient that soothes skin dryness

erythema

a change in skin color due to a change in blood flow

filiform wart

long, small, narrow growth that appears on the lips, face, or eyelids

flat wart

may appear in areas that are shaved or along stretch marks

folliculitis

an infection of the skin follicle

genital wart

(condyloma acuminata, venereal wart) occurs on the vagina, vulva, cervix, or penis

herpes simplex

viral infection that can cause painful blisters or ulcers

herpes zoster

(shingles) maculopapular rash associated with shingles most often appears on the trunk of the body along a thoracic dermatome

hydroxylation

the chemical process in which a hydroxyl group (–OH) is introduced into an organic compound

hyperpigmentation

darkened patches of skin (liver spots)

hypodermis

the subcutaneous fatty layer beneath the dermis that anchors the dermis to the underlying tissues of the body

hypopigmentation

lighter patches of skin (age spots)

impetigo

highly contagious bacterial skin infection that forms pustules and yellow crusty sores

Kaposi sarcoma

a rare type of cancer caused by a virus

keloid

a thick fibrous scar caused by excessive collagen formation in response to trauma or a surgical incision

keratin

fibrous water-repellant protein gives the epidermis its strong, protective quality

keratinization

a thickening of plasma membranes of a cell

keratinocyte

cell that produces keratin

Langerhans cell

antigen-processing cell that determines the appropriate response to (inflammation) or tolerance of foreign substances

maceration

the softening of tissues caused by prolonged wetting or soaking

malignant melanoma

the most dangerous type of skin cancer; originates in the melanocytes

melanin

dark brown to black pigment protects the keratinocytes and nerve endings from ultraviolet light damage that appears in the skin and hair

melanocyte

cell that produces melanin and keratinocyte

Merkel cell

found in the stratum basale and serves as a sensory receptor for light touch

mitotic activity

the degree in which a population of cells proliferates

MOHS procedure

layers of the skin are removed and examined for cancer cells until no signs of cancer remain

mosaic wart

wart that grows in clusters

nonbullous impetigo

type of impetigo that has pustules that rapidly break down and form thick, adherent, honey-colored crusts on the face and extremities

osteomalacia

bone demineralization

palmar wart

wart on the palm of the hand

papillary layer

thin, dermal layer of the dermis composed of loose connective tissue, which contacts the epidermis

pediculosis

lice infestation

pediculosis capitis

lice infestation of the scalp

pediculosis corporis

lice infestation of the body

pediculosis pubis

lice infestation of the hairs of the anal and genital areas but can also infest the thigh, chest, and facial hair

perspiration

(sweat) excess water and salts that are eliminated from the body via sweat glands

photodynamic therapy

using lasers and chemicals on the skin

pimple

has a small area of red skin and can be painful or cause discomfort

pityriasis

any of various skin conditions characterized by dry scaling patches of skin

plantar wart

wart on the sole of the foot

postinflammatory hyperpigmentation

temporary pigmentation that occurs after an injury or inflammatory skin condition, most commonly seen in people with darker skin types

prodromal state

period between the appearance of initial symptoms and the full development of an illness causing headache, malaise, chills, or photophobia

pruritus

itching

psoriasis

a recurring, chronic skin condition that causes one or more raised areas of red skin patches with silvery scales and a distinct border

pustule

similar to a pimple but contains white or yellow pus

Raynaud phenomenon

a condition that causes pale or blue fingers with cold exposure

reticular layer

thick, dermal layer of the dermis that consists of dense connective tissue, collagen bundles, and houses most of the sweat glands, sebaceous glands, hair follicles, hair, muscles, blood vessels, and deep sensory neurons

scabies

tissue that produces red and white blood cells and platelets; where hematopoiesis takes place

sebaceous gland

secretes sebum, an oily substance that makes the hair and skin waterproof

seborrheic dermatitis

inflammatory skin reaction primarily on the scalp and face

squamous cell carcinoma

the second most common type of skin cancer that generally develops on sun-exposed areas but can grow where sun exposure is limited

stratum basale

(stratum germinativum) deepest layer of the epidermis that contains melanocytes and keratinocytes

stratum corneum

thickest and outermost layer of the epidermis that secretes defensins as part of the body’s first immune defense

stratum granulosum

layer above the stratum spinosum that contains a glycolipid, which slows water loss across the epidermis

stratum lucidum

layer of skin only found in thick areas like the soles of the feet and palms of hands

stratum spinosum

layer above the stratum basale and contains cytoplasmic processes (spines) that extend outward and contact neighboring cells

subcutaneous tissue

the subcutaneous fatty layer (hypodermis) beneath the dermis that separates the skin from the underlying tissue

systemic lupus erythematosus (SLE)

a chronic autoimmune inflammatory disorder involving connective tissues of the joints, skin, kidneys, mucous membranes, and blood vessel walls

telangiectasias

red marks on the skin caused by the widening of shallow blood vessels

tenting

the skin does not snap back when pinched; instead, it maintains a tentlike shape, which may indicate dehydration

tinea

(ringworm) may be found on the feet, beard, body, groin, scalp, or toes

tinea barbae

(beard ringworm) fungal infection of the beard

tinea capitis

fungal infection of the scalp

tinea corporis

fungal skin infection of the arms, trunk, legs, and face

tinea cruris

fungal infection of the groin

tinea pedis

(athlete’s foot) fungal infection of the feet

tinea unguium

(onychomycosis) fungal infection of the toenail or fingernail

transdermal administration

placed on the skin and absorbed either locally or systemically

urticaria

(hives) rash of raised, swollen, flesh-colored or red bumps or welts on the skin

varicella

(chickenpox) caused by the varicella-zoster virus

verruca

(wart) raised or flat growth caused by the viral infection human papillomavirus

vesicle

small blister

vitiligo

chronic autoimmune disorder that causes partial or total loss of skin color in patches

whitehead

flesh-colored small bump that does not have a dark center

xerosis

skin dryness