The Integumentary System

Vocabulary practice flashcards for Chapter 5: The Integumentary System covering skin structure, epidermal layers, dermal structures, glands, hair, nails, skin colors, cancers, and burn classifications.

Integumentary System

The organ system composed of the skin and its derivatives (sweat glands, oil glands, hair, and nails) that primarily serves a protective role.

Epidermis

The outermost protective shield of the body, composed mainly of keratinized stratified squamous epithelial cells.

Dermis

The tough, leathery layer making up the bulk of the skin, composed mainly of dense connective tissue.

Hypodermis

The subcutaneous layer located deep to the skin (not technically part of the skin) that stores fat.

Keratinocytes

The most abundant cells of the epidermis that produce fibrous keratin protein to provide structure, durability, and waterproofing.

Melanocytes

Cells located in the deepest epidermal layer (10–25%) that synthesize the pigment melanin and package it into melanosomes to protect keratinocyte nuclei from UV damage.

Dendritic (Langerhans) cells

Epidermal macrophages that function as key activators of the immune system by presenting foreign antigens.

Tactile (Merkel) cells

Sensory touch receptors situated at the epidermal-dermal junction that associate with nerve endings in the dermis.

Stratum Basale

The deepest epidermal layer consisting of a single row of actively mitotic columnar stem cells firmly attached to the dermis.

Stratum Spinosum

The epidermal layer consisting of several cell layers of keratinocytes unified by desmosomes and containing thick bundles of intermediate prekeratin filaments.

Stratum Granulosum

A thin epidermal layer of four to six cell rows where keratinization begins, containing keratohyaline granules and lamellar granules.

Stratum Lucidum

A thin, translucent band of a few rows of flat, dead keratinocytes located superficial to the stratum granulosum, present only in thick skin.

Stratum Corneum

The most superficial epidermal layer consisting of 20–30 rows of dead, flat, anucleate keratinized cells that protect against abrasion, water loss, and penetration.

Papillary Layer

The superficial dermal layer composed of areolar connective tissue containing collagen, elastic fibers, blood vessels, and dermal papillae.

Dermal Papillae

Peg-like projections of the papillary dermis that contain capillary loops, free nerve endings, or tactile touch receptors.

Friction Ridges

Epidermal ridges created atop dermal ridges in thick skin that enhance gripping ability, contribute to tactile sense, and form fingerprints.

Reticular Layer

The deeper dermal layer comprising around 80% of dermal thickness, made of dense irregular connective tissue with elastic and collagen fibers.

Cleavage Lines

Externally invisible lines in the reticular dermis running parallel to less dense regions of collagen fibers, along which surgical incisions gap less and heal faster.

Flexure Lines

Dermal folds at or near joints where the dermis is tightly anchored to deeper structures, creating permanent skin creases.

Striae

Silvery-white dermal scars (stretch marks) caused by severe stretching that tears the dermal collagen fibers.

Blister

A fluid-filled pocket caused by acute trauma that separates the epidermal layer from the dermal layer.

Melanin

A skin pigment produced by melanocytes in shades from reddish yellow to brownish black that shields keratinocyte nuclei from UV damage.

Carotene

A yellow to orange pigment acquired from food (such as carrots) that accumulates in the stratum corneum and hypodermis and can be converted to Vitamin A.

Hemoglobin

The oxygen-binding pigment in red blood cells that provides the pinkish hue seen in fair skin.

Cyanosis

A bluish skin coloration resulting from poorly oxygenated blood, indicating heart failure, poor circulation, or severe respiratory illness.

Jaundice

A yellowing of the skin caused by accumulation of bile pigments in blood and tissues, indicating a liver disorder.

Erythema

Reddened skin caused by dilated blood vessels during fever, inflammation, allergy, or embarrassment.

Hair Medulla

The central core of a hair strand consisting of large, soft keratin-containing cells and air spaces.

Hair Cortex

The bulky middle layer of a hair strand surrounding the medulla, consisting of flattened cells.

Hair Cuticle

The heavily keratinized outermost layer of a hair strand consisting of single overlapping cells arranged like shingles.

Hair Matrix

The actively dividing germinal area of the hair bulb that produces new hair cells.

Arrector Pili

A smooth muscle bundle attached to a hair follicle that contracts to pull the hair into an upright position.

Vellus Hair

Fine, pale body hair typical of children and adult females.

Terminal Hair

Coarse, long hair found on eyebrows and scalp, and appearing in axillary and pubic regions at puberty.

Alopecia

Hair thinning occurring in both sexes after age 40 due to hair shedding faster than it is replaced.

Eccrine Sweat Glands

Simple coiled tubular glands abundant on the palms, soles, and forehead that secrete hypotonic sweat directly onto the skin surface.

Apocrine Sweat Glands

Larger sweat glands located in axillary and anogenital areas that secrete sweat containing fatty substances and proteins into hair follicles starting at puberty.

Ceruminous Glands

Modified apocrine sweat glands in the external ear canal that secrete earwax (cerumen).

Mammary Glands

Specialized modified sweat glands in female breasts that produce milk.

Sebaceous Glands

Simple branched alveolar glands present everywhere except thick skin that produce an oily secretion called sebum into hair follicles.

Sebum

An oily substance secreted by sebaceous glands that softens skin and hair, slows water loss, and has bactericidal properties.

Basal Cell Carcinoma

The least malignant and most common skin cancer, in which stratum basale cells proliferate and invade the dermis and hypodermis.

Squamous Cell Carcinoma

The second most common skin cancer, arising from the keratinocytes of the stratum spinosum and capable of metastasizing.

Melanoma

Cancer of melanocytes, which is highly metastatic, resistant to chemotherapy, and the most dangerous type of skin cancer.

ABCD Rule

A diagnostic standard for recognizing melanoma: Asymmetry, Border irregularity, Color variation, and Diameter greater than 6 mm.

Rule of Nines

A method used to calculate the percentage of body surface area affected by burns to estimate fluid loss and replacement needs.

First-degree Burn

A partial-thickness burn causing damage only to the epidermis, presenting with localized redness, swelling, and pain.

Second-degree Burn

A partial-thickness burn causing damage to the epidermis and upper dermis, marked by blister formation.

Third-degree Burn

A full-thickness burn involving all skin layers, appearing gray-white, cherry red, or blackened, and pain-free at the burn site due to nerve destruction.