Integumentary System Vocabulary

Vocabulary flashcards covering key terms, anatomical structures, layers, hair composition, exocrine glands, and clinical conditions outlined in Chapter 6 (Integumentary System).

Dermatology

The study of the skin.

Integument

The skin (cutaneous membrane), which acts as a barrier to the outside world, is the body's largest organ, and accounts for $7\text{--}8\%$ of total body weight.

Epidermis

The superficial layer of the integument composed of stratified squamous epithelium.

Dermis

The deeper layer of the integument located deep to the epidermis, primarily composed of dense irregular connective tissue.

Subcutaneous layer (hypodermis)

A layer deep to the dermis composed of areolar and adipose connective tissue that functions in protection, energy storage, and insulation; it is not part of the integumentary system.

Thick skin

Skin covering the palms of hands and soles of feet that contains all five epidermal strata and sweat glands, but lacks hair follicles and sebaceous glands.

Thin skin

Skin covering most of the body that lacks a stratum lucidum, but contains sweat glands, hair follicles, and sebaceous glands.

Hemoglobin

A red, oxygen-binding protein in red blood cells that gives blood vessels in the dermis a reddish tint in fair-skinned individuals.

Melanin

A dark pigment produced by melanocytes and transferred to keratinocytes; its production varies based on heredity and UV exposure.

Albinism

A condition in which melanocytes are unable to produce melanin.

Carotene

A yellow-orange pigment acquired from vegetables (such as yams and carrots) that is converted into Vitamin A, which is involved in vision, immune function, and reducing free radicals.

Nevus (mole)

A localized overgrowth of melanocytes that should be monitored for changes suggesting malignancy.

Freckles

Yellowish or brown spots that represent localized areas of increased melanocyte activity.

Hemangioma

Skin discoloration caused by a benign blood vessel tumor, such as strawberry-colored birthmarks or port-wine stains.

Friction ridges

Complex arches and whorls on fingers, palms, soles, and toes that increase friction on contact and allow for personal identification.

Papillary layer

The superficial region of the dermis composed of areolar connective tissue containing dermal papillae that interlock with epidermal ridges.

Reticular layer

The deeper, major portion of the dermis composed of dense irregular connective tissue.

Lines of cleavage (tension lines)

Identified orientations of collagen and elastic fiber bundles aligned in parallel to resist stress and stretch during routine movement.

Striae

Stretch marks resulting from torn collagen fibers when skin is stretched beyond its capabilities.

Transpiration

The process by which interstitial fluid penetrates through the epidermis to the surrounding air.

Calcitriol

An active hormone converted by the kidneys and liver from Vitamin $D_3$ (cholecalciferol) that increases absorption of calcium and phosphate in the small intestine.

Transdermal administration

A method of drug delivery where oil-soluble drugs are absorbed through the skin via an adhesive patch.

Epidermal derivatives

Accessory structures formed from portions of epidermal epithelium embedded into the dermis, including nails, hair, and exocrine glands.

Pilus

A single hair, composed of keratinized cells growing from a hair follicle.

Lanugo

Fine, unpigmented, downy hair present on a fetus.

Vellus

Fine, primary human hair found on upper and lower limbs.

Terminal hair

Coarser, pigmented, longer hair found on the scalp, eyebrows, eyelashes, and men's beards, which also replaces vellus hair in axillary and pubic regions during puberty.

Hair bulb

Swelling at the base of the hair in the dermis surrounding the hair papilla; it is the only region containing living epithelial cells.

Hair matrix

Structure at the base of the hair bulb where epithelial cells divide to produce new cells that push toward the surface.

Medulla

Remnant of the hair matrix consisting of flexible, soft keratin.

Cortex

Layer of flattened cells closer to the outer hair surface composed of relatively hard keratin.

Cuticle (hair)

A single cell layer surrounding the hair cortex.

Arrector pili

Thin ribbons of smooth muscle extending from the hair follicle to dermal papillae that contract to elevate the hair, creating "goosebumps".

Alopecia

Thinning of hair, usually occurring as a result of aging.

Hirsutism

Excessive male pattern hairiness.

Merocrine sweat glands

The most numerous sweat glands that discharge sensible perspiration directly onto the skin surface, serving a major role in thermoregulation.

Apocrine sweat glands

Sweat glands in the axillae, nipples, pubic, and anal regions that discharge viscous, cloudy secretions containing proteins and lipids into hair follicles starting at puberty.

Sebaceous glands

Holocrine glands that discharge an oily lubricant called sebum into hair follicles to lubricate skin and hair.

Ceruminous glands

Modified apocrine sweat glands located only in the external ear canal that produce waterproof earwax (cerumen).

Mammary glands

Modified apocrine sweat glands of the breast that produce breast milk in pregnant and lactating females.

Regeneration

Mode of tissue repair that replaces damaged or dead cells with the same cell type, fully restoring organ function.

Fibrosis

Mode of tissue repair where a gap is filled with scar tissue composed of collagen produced by fibroblasts, without restoring functional activities.

Rule of Nines

A clinical calculation used to estimate the percentage of total surface area affected by burns to help guide treatment decisions.

Botox

A facial wrinkle treatment using Clostridium botulinum toxin to temporarily block nerve impulses to facial muscles.