Integumentary System: Skin and Accessory Structures (Video)

Vocabulary flashcards covering the major skin structures, cells, layers, glands, and functional aspects from the video notes.

Epidermis

Avascular superficial layer of epithelial tissue nourished by diffusion from the dermis; composed of several strata.

Dermis

Deeper connective tissue layer that provides structural strength and houses nerves, blood vessels, hair follicles, and glands.

Subcutaneous tissue (hypodermis)

Loose connective tissue beneath the skin (not part of the skin) rich in adipose tissue; anchors skin to underlying structures and stores energy.

Keratinocytes

Most epidermal cells; produce keratin to strengthen the skin and resist abrasion.

Melanocytes

Pigment-producing cells that determine skin color by transferring melanin to keratinocytes.

Langerhans cells

Dendritic immune cells in the epidermis that help defend against pathogens.

Merkel cells

Touch receptor cells in the epidermis associated with tactile discs.

Desquamation

Process of shedding dead skin cells as they move toward the surface.

Keratinization

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

Stratum basale

Deepest epidermal layer; single layer with high mitotic activity, producing new keratinocytes.

Stratum spinosum

Several cell layers above basale; cells connected by desmosomes; appears spiny.

Stratum granulosum

Layer with keratohyalin granules; nuclei degenerate; cells begin to die and keratinize.

Stratum lucidum

Thin, clear layer found only in thick skin (palms and soles).

Stratum corneum

Most superficial epidermal layer of dead, cornified cells forming a protective barrier.

Thick skin

Skin with all five epidermal strata including stratum lucidum; found on palms and soles; contains fingerprints.

Thin skin

Skin lacking stratum lucidum; covers most of the body and usually has hair.

Papillary layer

Superficial dermal layer (areolar tissue) with dermal papillae; contains touch receptors.

Reticular layer

Deep dermal layer (dense irregular connective tissue) with collagen and elastic fibers; houses follicles and glands.

Dermal papillae

Dermis projections that create fingerprints and footprints; contain capillary beds and touch receptors.

Meissner’s corpuscles

Touch receptors located in the papillary dermis responsible for fine touch.

Tactile disc

Merkel cell touch receptor at the epidermal-dermal junction.

Cleavage (tension) lines

Directions of collagen/elastic fibers that affect wound healing; incisions parallel heal better.

Hair

Protein filament produced by hair follicles; provides protection and sense.

Hair follicle

Structure surrounding the hair root; includes dermal and epithelial root sheaths and hair bulb.

Hair bulb

Expanded, metabolically active base of the hair follicle; site of hair production.

Medulla

Central core of the hair shaft.

Cortex

Main bulk of the hair shaft; contains most of the keratin and pigment.

Cuticle (hair)

Outer layer of hair shaft; overlapping cells that protect inner layers.

Arrector pili

Smooth muscle attached to hair follicles; contraction makes hair stand (goosebumps).

Sebaceous gland

Holocrine glands that secrete sebum into hair follicles; lubricates hair and skin and has antimicrobial properties.

Sebum

Oily lipid secreted by sebaceous glands that keeps hair and skin moisturized.

Holocrine secretion

Secretory mode in which the whole secretory cell disintegrates to release product.

Eccrine (merocrine) sweat gland

Most common sweat gland; simple coiled tubular gland opening onto skin surface; produces isotonic sweat for thermoregulation.

Apocrine sweat gland

Coiled tubular gland with secretion into hair follicles; secretions become odorous when acted on by bacteria; active at puberty.

Ceruminous glands

Modified apocrine glands in the external ear canal; produce cerumen (earwax) to protect the ear.

Mammary glands

Modified apocrine sweat glands specialized for milk production.

Nails

Hard keratinized plates at the tips of fingers and toes; protect digits and aid in manipulation.

Nail body

Visible part of the nail composed of dead keratinized cells.

Nail matrix

Growth zone of the nail; cells divide to form the nail plate.

Nail root

Proximal part of the nail that extends under the skin and contributes to growth.

Eponychium

Also called the cuticle; the living skin at the base of the nail plate.

Hyponychium

Thickened skin under the free edge of the nail.

Hair growth rate

Average rate of hair elongation; about 0.3 mm/day (fingernails ~0.5–1.2 mm/day).

Hair color

Determined by varying amounts and types of melanin in the hair shaft.

Vitamin D production

Synthesis begins in the skin from 7-dehydrocholesterol under UV light and is converted to active calcitriol in liver/kidneys.

Calcitriol

Active form of vitamin D that promotes calcium and phosphate absorption and homeostasis.

Melanin

Pigment produced by melanocytes; protects against UV radiation and gives skin its color.

Carotene

Yellow-orange pigment from diet; accumulates in the stratum corneum and adipose tissue, contributing to color.

Albinism

Genetic deficiency or absence of pigment production, mainly melanin.

Cyanosis

Bluish skin color due to reduced oxygen in the blood.

Skin color factors

Determined by melanin, carotene, blood flow, and stratum corneum thickness.

Two-point discrimination

Ability to distinguish two close points on the skin as separate sensations; varies with dermal receptors.

Papillary vs. Reticular dermis

Papillary: superficial dermis with papillae and Meissner’s corpuscles; Reticular: deep dermis with dense connective tissue and hair glands.

Burns (first, second, third degree)

Classification by depth: first-degree (epidermis), second-degree (epidermis and part of dermis), third-degree (full thickness).

Rule of nines

Method to estimate total body surface area burned; proportions differ between adults and children.

Aging effects on the skin

Thinner epidermis, less collagen, wrinkling, dryness, reduced blood supply, and altered pigmentation with age.