Integumentary System – Skin & Accessory Structures

Vocabulary flashcards covering major structures, cell types, layers, and glands of the integumentary system.

Largest organ; composed of epidermis and dermis; protects, regulates temperature, synthesizes vitamin D/defensive proteins, and houses sensory receptors.

Skin (Cutaneous Membrane)

Superficial, avascular layer of stratified squamous keratinized epithelium; dominated by keratinocytes; forms barrier to chemical, microbial, and physical insults.

Epidermis

Deep layer of skin; dense connective tissue containing blood/lymph vessels, nerves, glands, and hair follicles; divided into papillary and reticular regions.

Dermis

Primary cell of epidermis that produces keratin through keratinization, giving skin toughness and water-resistance.

Keratinocyte

Process in which epidermal cells fill with keratin, die, and form a tough, protective outer layer.

Keratinization

Outermost epidermal layer; 25–30+ layers of dead keratinized cells; physical barrier to light, heat, microbes, chemicals; flakes off as dandruff.

Stratum Corneum

Clear epidermal layer present only in thick, hairless skin (palms, soles); 3–5 rows of dead, flat keratinocytes.

Stratum Lucidum

Granular epidermal layer (3–5 rows) with keratohyaline granules; active keratinization; secretes lipid sealant for water resistance.

Stratum Granulosum

‘Spiny’ epidermal layer (8–10 rows of keratinocytes) interconnected by desmosomes; provides strength and flexibility.

Stratum Spinosum

Deepest, single-cell epidermal layer attached to basement membrane; mitotically active; contains melanocytes.

Stratum Basale (Stratum Germinativum)

Pigment cell in stratum basale that produces melanin for skin color and UV protection.

Melanocyte

Superficial dermis made of areolar tissue; contains dermal papillae with capillaries, pain receptors, and Meissner’s corpuscles; forms fingerprints.

Papillary Region

Peg-like projections of papillary dermis that supply nutrients to epidermis and create dermal ridges for grip (fingerprints).

Dermal Papillae

Tactile receptor in papillary dermis sensitive to light touch.

Meissner’s Corpuscle

Deep dermis of dense irregular connective tissue; houses blood vessels, sweat/oil glands, and Pacinian corpuscles.

Reticular Region

Deep pressure, vibration, and texture receptor located in reticular dermis/subcutaneous tissue.

Pacinian (Lamellar) Corpuscle

Flexible strand of dead, keratinized cells; guards scalp, eyes, and respiratory tract; absent on palms, soles, nipples, lips.

Hair

Smooth muscle attached to hair follicle; contraction causes hair to stand (goosebumps).

Arrector Pili Muscle

Innermost, central core of hair shaft.

Medulla (Hair)

Middle, principal layer of hair containing pigment granules.

Cortex (Hair)

Outermost, heavily keratinized overlapping cells providing strength; wear causes split ends.

Cuticle (Hair)

Hard keratinized modification of epidermis; transparent but appears pink from dermal blood; grows faster on fingers than toes.

Nail

Whitish crescent at proximal nail body where thickened nail matrix obscures blood flow.

Lunula

Exocrine gland along hair follicles producing sebum; lubricates skin, prevents water loss, inhibits bacteria; activated at puberty, absent on palms/soles.

Sebaceous (Oil) Gland

Oily mixture from sebaceous glands that softens skin and hair and reduces water loss.

Sebum

Exocrine gland for thermoregulation and waste excretion; includes eccrine and apocrine types.

Sweat (Sudoriferous) Gland

Most numerous sweat gland; active soon after birth; produces watery (98% water) acidic sweat for cooling and excretion.

Eccrine (Merocrine) Gland

Larger sweat gland in axilla and genital areas; activated at puberty; secretes viscous fluid with fatty acids and proteins; odor develops via bacteria.

Apocrine Gland

Modified sweat gland of external ear canal producing wax (with sebaceous gland) to trap debris.

Ceruminous Gland