Integumentary System (Skin) - Vocabulary Flashcards

Vocabulary flashcards covering key terms related to the anatomy and physiology of the skin and its layers, cells, and color factors.

Integumentary system

The skin and its derivatives (hair, nails, glands) forming the body's outer covering.

Epidermis

Outer protective layer of skin made of stratified squamous epithelium; avascular.

Dermis

Deeper, vascularized layer of skin composed of dense irregular connective tissue; contains nerves, vessels, follicles, and glands.

Hypodermis (subcutaneous layer)

Layer beneath the skin, mostly adipose tissue; called superficial fascia; anchors skin to underlying structures.

Keratinocyte

Main epidermal cell that produces keratin; connected by desmosomes; originates in the stratum basale.

Keratin

Structural protein that provides protection to the epidermis.

Desmosome

Intercellular junction that binds keratinocytes together in the epidermis.

Melanocyte

Pigment-producing cell in the epidermis; synthesizes melanin; mainly in the stratum basale.

Melanin

Pigment giving skin color and providing UV protection.

Langerhans cell (Dendritic cell)

Epidermal macrophage-like immune cell; engulfs foreign substances.

Merkel cell (Tactile cell)

Touch-sensing cells in the epidermis associated with sensory nerve endings.

Stratum basale

Deepest epidermal layer; single row of actively mitotic stem cells; site of new keratinocytes.

Stratum spinosum

Several cell layers with desmosomes; gives a spiny appearance; contains keratinocytes, Langerhans cells, and melanin granules.

Stratum granulosum

1–5 cell layers where keratinization begins; keratin and lamellar granules form to waterproof.

Lamellar granules

Glycolipid-containing bodies that waterproof the skin and slow water loss.

Keratinization (cornification)

Process by which keratinocytes accumulate keratin and die, forming the stratum corneum.

Stratum lucidum

Clear layer found only in thick skin; 2–3 rows of dead keratinocytes.

Stratum corneum

Outermost epidermal layer; 20–30 rows of dead keratinized cells; major barrier.

Thick skin

Skin with five epidermal layers; located on palms and soles.

Thin skin

Skin with four epidermal layers; covers most of the body.

Dermal papillae

Projections of the dermis into the epidermis containing capillary loops; create fingerprints.

Papillary layer

Superficial dermal layer of areolar connective tissue; contains dermal papillae and defensive cells.

Reticular layer

Deeper dermal layer of dense irregular connective tissue; contains collagen and elastic fibers; provides strength and elasticity.

Areolar connective tissue

Loose connective tissue in the papillary layer supporting the epidermis.

Collagen

Structural protein providing strength; binds water; forms cleavage lines.

Elastic fibers

Fibers in the dermis that provide elasticity and recoil; degraded by UV exposure.

Cleavage lines

Tension lines in the skin; incisions parallel to lines heal with less scarring.

Carotene

Yellow–orange pigment from diet; accumulates in stratum corneum and hypodermis; converted to vitamin A.

Hemoglobin

Oxygen-carrying pigment in blood contributing to skin color; more visible in light skin.

Cyanosis

Blue discoloration of skin due to low oxygen.

Erythema

Redness of skin due to embarrassment, inflammation, fever, or hypertension.

Pallor

Paleness of skin due to anemia, low blood pressure, fear, or anger.

Jaundice

Yellow skin due to bilirubin buildup; liver dysfunction.

Bronzing

Bronze coloration of skin due to adrenal insufficiency (Addison’s disease) or poor steroid hormones.

Bruise

A hematoma under the skin from escaped blood after vessel damage.

Sebaceous glands

Oil glands in the skin; secrete sebum; usually associated with hair follicles.

Sudoriferous glands

Sweat glands (eccrine and apocrine) in the skin; help thermoregulation.

Hair follicles

Dermal structures derived from epidermal tissue that produce hair.

Turnover rate of epidermis

The epidermis renews about every 25–45 days; ~50 million cells shed daily; ~7% body weight.

Diffusion of nutrients to epidermis

Epidermis is avascular; nutrients reach it by diffusion from the dermis.