The Integumentary System - Lesson 5

Comprehensive vocabulary flashcards covering the anatomy, histology, cellular components, appendages, pathology, and burn assessments of the integumentary system based on Lesson 5 lecture notes.

Epidermis

The superficial layer of the skin composed of epithelial tissue.

Dermis

The deep layer of the skin composed of connective tissue.

Sub-Q (Subcutaneous Layer)

A layer of adipose tissue located deep to the dermis that is not considered part of the skin.

Stratum Basale

The deepest epidermal layer consisting of a single layer of actively dividing cuboidal cells that push older cells toward the surface, and where melanocytes are present.

Stratum Spinosum

An epidermal layer characterized by a 'spiny' appearance caused by desmosomes anchoring cells together, where melanin shields nuclear DNA from UV damage.

Stratum Granulosum

An epidermal layer consisting of $5\text{ to }7$ layers of darkly staining cells filled with granules containing keratin and lamellin, in which cells flatten, organelles disintegrate, and cells die.

Stratum Lucidum

A clear epidermal layer found exclusively in thick skin on the palms and soles, consisting of flattened, dead keratinocytes.

Stratum Corneum

The outermost 'horny' layer that makes up most of epidermal thickness, composed of many layers of dead, flattened cells containing keratin that shed regularly to protect against abrasion, penetration, and water loss.

Keratinocytes

The most abundant epidermal cells, responsible for producing keratin to provide durability and physical protection.

Melanocytes

Specialized cells found mostly in the stratum basale that synthesize melanin to protect cellular DNA from UV radiation.

Dendritic cells (Langerhans's Cells)

Cells originating in the bone marrow that migrate to the epidermis to ingest foreign material and activate the immune system.

Merkel cells (Tactile Epithelial Cells)

Touch-sensing receptor cells situated at the epidermal-dermal junction.

Papillary layer

The superficial layer of the dermis composed of areolar connective tissue that underlies the epidermis and forms dermal papillae.

Dermal papillae

Fingerlike projections of the papillary dermis into the epidermis that contain capillary loops, free nerve endings, and Meissner's corpuscles.

Capillary loops

Tiny blood vessels located within the dermal papillae that supply nutrients to the avascular epidermis.

Meissner's corpuscles

Sensory receptors specialized for light touch, situated within the dermal papillae of the papillary dermis.

Free nerve endings

Nerve endings located in the papillary dermis that function as pain receptors.

Friction ridges

Epidermal ridges on the palms and soles caused by underlying dermal ridges, commonly known as fingerprints, which enhance gripping ability.

Reticular layer

The deeper layer of the dermis composed of dense irregular connective tissue, featuring bundles of collagen fibers that mostly run parallel to the skin surface.

Cleavage lines

Separations between bundles of collagen fibers in the reticular dermis; surgical incisions made parallel to these lines heal more rapidly.

Melanin

A UV-stimulated pigment synthesized by melanocytes; differences in skin color stem from the type, quantity, and cellular retention of melanin rather than melanocyte cell count.

Carotene

A yellow-orange plant pigment that accumulates in the stratum corneum and subcutaneous adipose tissue.

Hemoglobin

An oxygen-binding blood pigment that imparts a pinkish hue to fair skin as light penetrates the translucent epidermis.

Jaundice

A yellowish pigmentation of the skin caused by the abnormal accumulation of bilirubin.

Cyanosis

A bluish discoloration of the skin resulting from inadequate oxygenation of hemoglobin.

Hair shaft

The visible portion of hair that projects above the surface of the skin, composed of dead cells filled with hard keratin.

Hair root

The structural portion of the hair that remains embedded within the skin.

Hard keratin

A durable, tough protein found in hair and nails that does not flake off like the soft keratin of epidermal skin cells.

Arrector pili

A bundle of smooth muscle attached to a hair follicle that pulls the hair erect upon contraction.

Hair matrix

The zone of actively dividing cells adjacent to the hair papilla responsible for generating new hair growth.

Medulla (Hair)

The innermost central core of a hair strand that contains soft keratin.

Cortex (Hair)

The intermediate layer of a hair strand consisting of multiple layers of flattened cells that receive pigment granules from melanocytes.

Cuticle (Hair)

The outermost hair layer composed of a single sheet of overlapping, shingle-like cells.

Vellus hair

Fine, pale body hair typically found covering women and children.

Terminal hair

Coarse, thicker, and darker hair located on the scalp, eyebrows, and eyelashes, which proliferates in axillary and pubic regions at puberty in response to androgens.

Eccrine sweat glands

Widely distributed sweat glands functioning in excretion and thermoregulation that secrete a slightly acidic, mostly water-based solution containing salts, nitrates, and wastes.

Apocrine sweat glands

Sweat glands confined to axillary and anogenital regions that empty into hair follicles, producing an androgen-regulated secretion broken down by surface bacteria to generate body odor.

Sebaceous glands

Oil glands located across most of the body (excluding palms and soles) that secrete sebum into hair follicles to provide lubrication and bactericidal properties.

Nail matrix

The proximal thickened area of the nail bed responsible for cellular proliferation and nail plate growth.

Lunula

The white, crescent-shaped region situated at the base of the nail body.

Eponychium

The proximal nail fold projection commonly referred to as the cuticle.

Hyponychium

The region of epidermis located beneath the free edge of the nail.

Basal Cell Carcinoma

The most common and slow-growing form of skin cancer arising in the stratum basale, presenting as a pearly white, pink, or skin-colored bump that may rupture, bleed, and scab.

Squamous Cell Carcinoma

A skin malignancy arising from keratinocytes in the stratum spinosum, typically appearing on the head or hands as a firm red nodule or scaly reddened patch that can metastasize.

Melanoma

A dangerous malignancy characterized by rapid melanocyte proliferation, early metastasis, chemoresistance, and presentation as a spreading brown-black lesion.

ABCDE Rule

A diagnostic mnemonic for melanoma detection evaluating Asymmetry, irregular Border, mixed Color, Diameter larger than $1/4\,\text{inch}$ ($6\,\text{mm}$), and Evolving characteristics over time.

First-Degree Burn

A superficial burn limited to the epidermis that causes localized redness, swelling, and pain (such as a sunburn) and heals within several days.

Second-Degree Burn

A partial-thickness burn damaging the epidermis and upper dermis, resulting in redness, swelling, pain, and blisters, typically healing within $3\text{ to }4\,\text{weeks}$.

Third-Degree Burn

A full-thickness burn destroying the epidermis, dermis, and sometimes hypodermis; lesions lack pain sensation due to destroyed nerve endings and require skin grafting.

Rule of Nines

A clinical calculation tool that divides the human body surface area into increments of $9\%$ to estimate burn extent and determine fluid and nutritional requirements.