TEAS Integumentary

Function of skin

Acts as a protective barrier against pathogens, UV radiation, and mechanical injury; regulates body temperature; prevents water loss; and senses environmental stimuli.

Epidermis

The outermost, avascular layer of the skin composed of stratified squamous epithelium that provides waterproof protection.

Keratinocytes

The predominant cells of the epidermis that produce the tough, fibrous protein keratin.

Langerhans cells

Dendritic immune cells in the epidermis that engulf pathogens and initiate immune responses.

Melanocyte

Specialized pigment-producing cells in the stratum basale that synthesize melanin to protect skin from UV radiation.

Cornified

A process where cells accumulate keratin, harden, and die to form a tough, protective outer layer (keratinization).

Stratum corneum

The outermost layer of the epidermis consisting of dead, flattened, keratinized cells that form a tough physical barrier.

Stratum lucidum

A thin, clear, translucent layer of dead keratinocytes found only in the thick skin of the palms and soles.

Stratum granulosum

A layer of the epidermis where keratinocytes contain dark granules of keratin and lipids, marking the start of cell death.

Stratum spinosum

A thick epidermal layer characterized by spiny-looking cell junctions (desmosomes) that provide structural strength.

Stratum basale

The deepest layer of the epidermis containing actively dividing stem cells, melanocytes, and Merkel cells.

Dermis

The thick, vascular inner layer of skin beneath the epidermis containing connective tissue, hair follicles, glands, and nerve endings.

Fibroblasts

Specialized connective tissue cells in the dermis that secrete collagen and elastin fibers to maintain structural integrity.

Papillary layer

The upper, superficial layer of the dermis featuring finger-like projections that create fingerprints and nourish the epidermis.

Reticular layer

The deeper, thicker layer of the dermis composed of dense irregular connective tissue that provides strength and elasticity.

Scars

Fibrous connective tissue composed mainly of collagen that replaces normal skin following injury or deep wounds.

Keloid

An overgrowth of dense, raised fibrous scar tissue that extends beyond the original boundaries of a wound.

Adipose tissue

Loose connective tissue composed of fat cells located in the hypodermis, providing insulation and energy storage.

Sweat glands

Tubular exocrine glands in the dermis that produce sweat to regulate body temperature and excrete waste.

Vasodilation

The widening of blood vessels near the skin surface to increase blood flow and dissipate excess body heat.

Vasoconstriction

The narrowing of blood vessels near the skin surface to reduce blood flow and conserve core body heat.

Sebaceous glands

Exocrine glands in the dermis connected to hair follicles that secrete oily sebum to lubricate and waterproof skin and hair.

Arrector Pili muscle

Tiny smooth muscle bundles attached to hair follicles that contract to pull hair upright (goosebumps) and squeeze sebum.

Pacinian corpuscle

Deep dermal mechanoreceptors sensitive to deep pressure and high-frequency vibration.

Meissner’s corpuscle

Superficial mechanoreceptors in dermal papillae sensitive to fine touch, light pressure, and low-frequency vibration.

Free nerve ending

Unencapsulated nerve endings extending into the epidermis that sense pain, temperature, and crude touch.

Hair follicle

A tubular sheath of epidermal tissue surrounding the root of a hair, anchoring it within the dermis.

Hair root

The portion of a hair embedded beneath the skin surface inside the hair follicle.

Hair shaft

The visible portion of the hair extending outward beyond the surface of the skin.

Dermal papilla

A cluster of capillaries and connective tissue at the base of a hair follicle that provides nutrients to growing hair.

Keratin

A tough, fibrous, water-resistant protein that forms the primary structural material of hair, nails, and outer skin.

Collagen

A major structural protein in the dermal extracellular matrix that provides tensile strength and durability to the skin.

Elastin

A protein fiber in the dermis that allows skin to stretch and passively recoil back to its original shape.

Dense irregular connective

A type of connective tissue with randomly arranged collagen fibers found in the reticular layer of the dermis.

Nail plate

The hard, translucent, keratinized visible part of the nail.

Nail root

The hidden portion of the nail beneath the skin surface where nail production originates.

Nail matrix

The actively dividing germinative zone beneath the nail root responsible for nail growth.

Nail bed

The specialized layer of epidermal tissue beneath the nail plate that supports the growing nail.

Cuticle

A fold of stratum corneum (eponychium) that seals and protects the proximal edge of the nail plate.

Hypodermis

The subcutaneous layer beneath the dermis containing adipose and loose connective tissue that anchors skin to deeper structures.

Skin cancer

Uncontrolled abnormal growth of skin cells, primarily caused by cumulative UV radiation damage.

Melanoma

A dangerous, aggressive form of skin cancer originating from uncontrolled proliferation of pigment-producing melanocytes.

Carcinoma

A common type of skin cancer originating from epithelial cells, including basal cell and squamous cell carcinomas.

First degree burn

A superficial burn damaging only the outer epidermis, causing redness, pain, and minor swelling without blistering.

Second degree burn

A partial-thickness burn damaging the epidermis and upper dermis, characterized by severe pain, redness, and blistering.

Third degree burn

A full-thickness burn destroying both the epidermis and entire dermis, often appearing white or charred with nerve damage.

Fourth degree burn

A catastrophic full-thickness burn extending completely through skin layers down to underlying muscle, tendons, and bone.

Ceruminous glands

Specialized modified sweat glands located in the external ear canal that produce waxy cerumen (earwax).

Eccrine glands

Widely distributed merocrine sweat glands that secrete a watery fluid directly onto the skin surface to regulate temperature.

Apocrine glands

Specialized sweat glands found in the armpits and groin that secrete a thicker, odorous fluid in response to stress or hormones.