Integumentary System ''

Vocabulary flashcards covering the structure, function, accessory organs, pigmentation, aging, common diseases, and injuries of the integumentary system as described in the notes.

Integumentary system

The skin and its accessory structures; the largest organ system responsible for protection, sensation, and other functions.

Epidermis

The outer, avascular layer of the skin made of keratinized stratified squamous epithelium with four or five layers.

Keratinocyte

The main epidermal cell type that manufactures keratin; most epidermal cells, with the deepest ones alive and the superficial ones often dead.

Stratum basale (basal layer)

Deepest epidermal layer; a single layer of basal cells that divide to produce keratinocytes; contains Merkel cells and melanocytes; attaches to the basement membrane.

Merkel cell

Touch receptor cell in the stratum basale, involved in light touch perception.

Melanocyte

Pigment-producing cell in the epidermis that synthesizes melanin and transfers pigment to keratinocytes.

Melanin

Pigment that gives color to skin and hair and helps protect skin cells from UV damage.

Stratum spinosum

Spiny layer above the basale; keratinocytes connected by desmosomes; contains Langerhans cells and begins keratin production.

Langerhans cell

Dendritic immune cell in the stratum spinosum that engulfs microbes and debris.

Stratum granulosum

Layer where keratinocytes flatten and accumulate keratin and keratohyalin; contains lamellar granules for waterproofing.

Keratin

Fibrous protein in keratinocytes that strengthens skin, hair, and nails and provides water resistance.

Keratohyalin

Protein in the stratum granulosum that aids in keratinization.

Lamellar granules

Secretory granules releasing lipids to form a waterproof barrier in the stratum granulosum.

Stratum lucidum

Clear layer found only in thick skin; dead keratinocytes containing eleidin.

Stratum corneum

Outermost, dead keratinized cell layer; 15–30 layers; provides a tough, waterproof barrier and protection.

Thick skin

Skin with five epidermal layers, including stratum lucidum; found on the palms and soles.

Dermis

Middle, fibrous skin layer containing blood vessels, nerves, hair follicles, and glands; two sublayers: papillary and reticular.

Papillary layer

Superficial dermal layer of loose areolar connective tissue with dermal papillae and capillaries.

Dermal papillae

Finger-like projections of the papillary layer that extend into the epidermis, strengthening the connection and forming fingerprints.

Meissner’s corpuscle

Touch receptor located in the papillary layer, sensitive to light touch.

Reticular layer

Deeper dermal layer of dense irregular connective tissue; provides strength and elasticity; houses glands and hair follicles.

Hypodermis (subcutaneous layer)

Layer beneath the dermis; not part of the skin proper; contains adipose and loose connective tissue; anchors skin and provides insulation and energy storage.

Hair follicle

Structure that extends from the epidermis into the dermis; surrounds the growing hair.

Hair shaft

Visible part of the hair that extends above the skin surface.

Hair root

Part of the hair located within the follicle, ending at the hair bulb.

Hair bulb

Enlarged base of the hair follicle where hair growth originates; contains the hair matrix.

Hair papilla

Connective tissue with blood vessels and nerves at the base of the hair follicle.

Hair matrix

Layer of basal cells in the hair bulb that produces new hair cells for growth.

Medulla, Cortex, Cuticle (hair structures)

Internal hair layers: medulla (central core, often absent), cortex (bulk of keratin), and cuticle (outer protective layer); arrangement affects texture.

Arrector pili

Small smooth muscle that makes hair stand up (goosebumps) in response to nerves.

Hair color

Determined by melanin produced by melanocytes in the hair matrix.

Nails

Keratinized plates on the fingertips and toes; protect tips and aid in grasping.

Nail bed

Skin beneath the nail plate rich in blood vessels; gives pink color.

Lunula

Pale crescent-shaped area at the base of the nail.

Cuticle (eponychium)

The skin fold at the proximal nail border that protects the nail root.

Hyponychium

Thickened epidermal region under the free edge of the nail.

Sebaceous gland

Oil-producing gland associated with hair follicles; secretes sebum to lubricate skin and hair; activated by hormones.

Eccrine (merocrine) sweat gland

Sweat gland that produces a watery, hypotonic sweat for thermoregulation; found nearly all over the skin.

Apocrine sweat gland

Sweat gland in hairy areas that produces thicker secretions containing organic compounds; involved in body odor and hormonal signaling.

Sebum

Oily secretion from sebaceous glands that lubricates skin and hair and has antibacterial properties.

Vitamin D synthesis

Skin uses UV light to convert 7-dehydrocholesterol to vitamin D3 (cholecalciferol), later activated in liver and kidney to calcitriol, essential for calcium absorption.

Rickets

Vitamin D deficiency in children causing bone deformities; soft, weak bones.

Osteomalacia

Vitamin D deficiency in adults leading to soft bones.

Albinism

Genetic condition with little or no melanin production; pale skin, hair, and eyes; increased UV sensitivity.

Vitiligo

Patchy loss of skin pigment due to melanocyte dysfunction or autoimmune processes.

Jaundice

Yellowing of the skin and eyes due to bilirubin buildup, often from liver disease.

Melanoma

Most dangerous skin cancer; malignant growth of melanocytes; highly metastatic; often arises from a mole.

Basal cell carcinoma

Most common skin cancer; arises from basal cells in the epidermis; usually slow-growing and Sun-exposed; treated by surgery or topical methods.

Squamous cell carcinoma

Skin cancer from keratinocytes of the stratum spinosum; more aggressive and can metastasize; treated with surgery or radiation.

ABCD (melanoma signs)

Asymmetry, Border irregularity, Color variation, Diameter >6 mm; evolving in size/shape; used to evaluate melanoma risk.

Eczema (atopic dermatitis)

Inflammatory, itchy dry patches of skin; often linked to allergies; treated with moisturizers and anti-inflammatory medications.

Acne

Inflammation of hair follicles due to clogged pores, excess sebum, hormones, and bacteria; common in adolescence.

Warts

Viral skin infection causing small rough growths on the skin.

Dermatologist

Medical doctor who specializes in diagnosing and treating skin conditions; may perform procedures and cosmetic treatments.

Bedsores (decubitus ulcers)

Pressure-induced skin and tissue damage, common in immobile individuals; prevent with frequent repositioning and wound care.

Callus and corn

Thickened skin from repeated friction; callus forms on weight-bearing surfaces; corn is a specialized callus due to localized pressure.

Stretch marks (striae)

Tearing of dermal collagen due to rapid stretching; reddish at first, then fade.