The Integumentary System

A comprehensive vocabulary review of the integumentary system covering skin layers, epidermal strata, pigments, sunlight synthesis, skin cancers, sensory receptors, hypodermis, hair anatomy, and exocrine glands.

Cutaneous Membrane

The multi-layered skin structure consisting of the epidermis, dermis (papillary and reticular layers), and underlying subcutaneous layer (hypodermis).

Accessory Structures

Structures of the integumentary system that include hair, nails, and exocrine glands.

Stratum Corneum

The outermost epidermal layer composed mostly of dead skin cells containing keratin, providing protection from heat damage, UV radiation, and water loss.

Desquamation

The natural process of shedding dead skin cells from the stratum corneum.

Stratum Lucidum

A clear, breakable epidermal layer that reduces friction between adjacent strata, found exclusively in thick skin such as the palms of the hands and soles of the feet.

Stratum Granulosum

The middle layer of the epidermis that forms a waterproof barrier between the inner and outer epidermal layers.

Stratum Spinosum

Known as the prickly layer due to cell junctions, this layer is where keratinization begins and contains immune-functioning Langerhans cells.

Langerhans Cells

Cells located in the stratum spinosum that assist in fighting skin infections and promoting healing.

Stratum Germinativum (Stratum Basale)

The deepest layer of the epidermis responsible for producing new cells that push upward and differentiate from cuboidal to squamous cells.

Carotene

An orange-yellow pigment found in the epidermis that can be converted into Vitamin A, essential for epithelial maintenance and synthesizing photoreceptor pigments in the eye.

Melanin

A brown, yellow-brown, or black pigment produced by melanocytes that shields the skin from damage by absorbing UV radiation.

Albinism

A genetic condition characterized by the inability of melanocytes to produce melanin.

Calcitriol

A hormone synthesized by the kidneys from modified Vitamin D3 that is essential for calcium and phosphorus absorption in the small intestine.

Rickets

A disorder causing weak and flexible bones resulting from an inadequate supply of Vitamin D3.

Basal Cell Carcinoma

The most common form of skin cancer, originating from the basal cell layer of the epidermis.

Squamous Cell Carcinoma

A form of skin cancer that involves the superficial layers of the epidermis.

Malignant Melanoma

A life-threatening, aggressive skin cancer arising from cancerous melanocytes that grow rapidly and can invade other regions of the body.

Papillary Layer

The superficial layer of the dermis composed of loose connective tissue, containing capillaries to supply nutrients and oxygen and nerve fibers for sensation and blood flow regulation.

Reticular Layer

The deep layer of the dermis composed of dense irregular connective tissue with elastic fibers for flexibility and collagen fibers to prevent tissue damage, housing glands and hair follicles.

Pacinian Corpuscle

A dermal sensory receptor specialized in detecting vibrations.

Meissner's Corpuscle

A dermal sensory receptor specialized in detecting light touch.

Merkel Disks

Sensory nerve structures in the skin that detect deep pressure.

Ruffini Corpuscles

Sensory receptors located in the dermis that detect stretching.

Hypodermis (Subcutaneous Layer)

A layer of loose connective tissue and fat cells beneath the dermis that cushions shocks, stores energy, stabilizes the skin over muscle, and lacks vital organs.

Dermal Papilla (Hair Papilla)

A small peg of connective tissue at the base of the hair follicle containing capillaries and nerves to nourish growing hair.

Hair Root

The portion of the hair located beneath the surface that anchors the hair into the skin.

Hair Shaft

The visible portion of the hair extending beyond the skin surface, organized into three concentric layers: the cuticle, cortex, and medulla.

Cuticle (Hair)

The outermost surface layer of the hair shaft consisting of overlapping keratinized cells.

Cortex (Hair)

The middle layer of the hair shaft that contains pigment granules and retains moisture.

Medulla (Hair)

The central core layer of the hair shaft that contains soft keratin.

Arrector Pili Muscle

A bundle of smooth muscle attached to the hair follicle that contracts in response to cold or emotional stimuli, elevating the hair and producing goosebumps.

Sebaceous Glands

Exocrine oil glands that secrete sebum into hair follicles or onto the skin surface to lubricate tissues and inhibit bacterial growth, whose activity increases during puberty.

Sebum

An oily lipid secretion produced by sebaceous glands that lubricates the skin and hair while inhibiting bacterial growth.

Apocrine Sweat Glands

Sweat glands producing a sticky, cloudy, and potentially odorous secretion containing pheromones, which produces an odor when metabolized by surface bacteria.

Merocrine (Eccrine) Sweat Glands

Numerous and widely distributed sweat glands that secrete water and electrolytes to cool the body, dilute chemicals, and flush unwanted bacteria using dermicidin.

Dermicidin

An antibiotic peptide secreted by merocrine sweat glands that flushes and destroys unwanted bacteria on the skin surface.