Structure of the Largest Organ in the Body - Integumentary System

Vocabulary practice flashcards covering the anatomy, cell types, strata, dermal layers, accessory structures, and clinical aspects of the integumentary system.

Integumentary System

The organ system that acts as a protective barrier against chemical and biological agents and physical abrasions, helps regulate body temperature, houses cutaneous sensory receptors, and produces oil, sweat, and vitamin D precursors.

Epidermis

The superficial, avascular skin region composed of keratinized, stratified squamous epithelium.

Dermis

The strong, flexible middle skin layer composed of dense irregular connective tissue that binds the body together and houses nerves, blood vessels, hair follicles, glands, and lymphatic vessels.

Hypodermis

The subcutaneous layer composed of adipose tissue and collagen that stores fat, provides insulation, contains larger blood vessels and nerves, and allows movement between the skin and underlying muscles and organs.

Stratum Corneum

The most superficial epidermal stratum, consisting of 20 to 30 layers of dead, flattened, avascular cells that form a protective outer barrier.

Stratum Lucidum

A clear, thin band of dead cells packed with transparent protein, found only in the thick skin of high-abrasion areas such as the palms and soles.

Stratum Granulosum

An epidermal layer consisting of 3 to 5 layers of cells filled with keratin that become flattened and granular in appearance due to distance from blood vessels.

Stratum Spinosum

An epidermal layer composed of 8 to 10 layers of living cells that produce pre-keratin, begin to lose water, and develop a spiky appearance; also contains dendritic cells.

Stratum Basale

The deepest single layer of epidermal cells closest to capillary blood supply that actively divides via mitosis to generate new skin cells.

Keratinocytes

The primary cells of the epidermis that produce keratin, a fibrous protein that imparts water-proofing and protective qualities to the skin.

Dendritic Cells

Immune cells residing in the stratum spinosum that patrol for and defend against foreign invaders.

Melanocytes

Cells located in the stratum basale that synthesize melanin, a pigment-protein that shields keratinocyte nuclei from damaging ultraviolet (UV) light.

Merkel Cells

Fine touch receptor cells situated in the stratum basale of the epidermis.

Melanin

A pigment-protein ranging from reddish yellow to brownish black produced by melanocytes to protect cell nuclei from UV radiation, whose varying amounts and forms account for diversity in skin tones.

Papillary Layer

The superficial, bumpy layer of the dermis composed of areolar connective tissue that anchors to the epidermis and contains capillaries, lymphatic vessels, and Meissner corpuscles.

Reticular Layer

The deep layer of the dermis composed of dense connective tissue with collagen and elastin fibers; contains hair follicles, oil glands, sweat glands, large blood vessels, and lamellar corpuscles.

Meissner Corpuscles

Tactile touch corpuscles located in the papillary layer of the dermis.

Lamellar (Pacinian) Corpuscles

Deep pressure receptors situated in the reticular layer of the dermis.

Pressure Ulcers (Bed Sores)

Sores caused by sustained pressure against a hard surface that stops localized blood flow, commonly developing over bony projections with minimal fat padding and leading to inflammation and open wounds.

Sebaceous Glands

Epithelial oil glands found throughout the dermis (except in thick skin) that secrete sebum into hair follicles to soften skin and hair, kill bacteria, and bind dead keratinocytes.

Eccrine Sweat Glands

The most numerous sweat glands in the dermis, featuring ducts that empty directly onto skin surface pores to secrete sweat (water, salt, wastes, and vitamins) for thermoregulation.

Apocrine Sweat Glands

Large sweat glands located in the axillary and inguinal regions whose ducts empty into hair follicles, producing a milky or yellowish fat- and protein-rich sweat during stress and sexual activity that produces body odor when degraded by bacteria.

Mammary Glands

Specialized skin glands present in both sexes but functionally developed only in females to produce milk for a newborn.

Hair Shaft

The portion of a hair that projects superficially beyond the epidermal surface of the skin.

Hair Root

The portion of a hair embedded beneath the surface within the epidermis and dermis.

Hair Bulb

The expanded structure at the distal base of the hair root that contains blood vessels and actively dividing cells within the hair papilla.

Hair Follicle

An epithelial tube made of an epithelial root sheath and dermal root sheath that encloses the hair root.

Arrector Pili

A small smooth muscle bundle attached to a hair follicle that pulls the hair erect for thermoregulation or during fight-or-flight scenarios.

Fibroblasts

Dermal cells that absorb and retain tattoo ink particles suspended within the dermis, giving tattoos their permanence.