Integumentary System Lecture Flashcards

Comprehensive vocabulary flashcards covering the key terms, structural layers, cell types, functions, epidermal derivatives, and repair mechanisms described in the Integumentary System lecture transcript.

Integumentary System

The organ system that covers the body and consists of the skin (integument) and its accessory tissues, including nails, hair, sweat glands, and sebaceous glands.

Dermatology

The scientific study of the skin.

Integument

The cutaneous membrane or skin, which serves as the body's largest organ, accounting for 7\text{ to }8\text{\textpercent} of total body weight.

Epidermis

The superficial layer of the integument consisting of keratinized, stratified squamous epithelium.

Dermis

The deeper layer of the integument, measuring $0.5\text{ mm}$ to $3.0\text{ mm}$ in thickness, primarily composed of dense irregular connective tissue.

Subcutaneous Layer

Also called the hypodermis or superficial fascia; a layer deep to the dermis composed of areolar and adipose connective tissue that is not part of the integumentary system.

Stratum Basale

The deepest epidermal layer consisting of a single layer of cuboidal to low columnar cells attached to the basement membrane.

Keratinocytes

The most abundant cells in the epidermis, found in all layers, responsible for synthesizing the strengthening protein keratin.

Melanocytes

Cells scattered among keratinocytes in the stratum basale that produce and store melanin pigment in melanosomes to shield nuclear DNA from UV light.

Tactile Cells

Also called Merkel cells; few, scattered cells in the stratum basale sensitive to touch that release chemicals to stimulate sensory nerve endings upon compression.

Stratum Spinosum

The spiny layer of the epidermis consisting of several layers of polygonal, non-dividing keratinocytes attached by desmosomes.

Epidermal Dendritic Cells

Also called Langerhans cells; immune cells found in the stratum spinosum and stratum granulosum that initiate an immune response against pathogens and cancer cells.

Stratum Granulosum

The granular layer of the epidermis comprising $3\text{ to }5$ layers of keratinocytes where keratinization begins.

Keratinization

The process in which keratinocytes fill with keratin, causing their nucleus and organelles to disintegrate and leading to cell death.

Stratum Lucidum

A translucent, clear layer of $2\text{ to }3$ cell layers found only in thick skin on the palms and soles, filled with the protein eleidin.

Eleidin

A translucent protein in the stratum lucidum that serves as an intermediate product in keratin maturation and helps protect against UV light.

Stratum Corneum

The most superficial hornlike layer of the epidermis consisting of $20\text{ to }30$ layers of dead, anucleate, interlocking keratinized cells.

Thick Skin

Skin type found on the palms of hands and soles of feet that contains all five epidermal strata, houses sweat glands, lacks hair follicles and sebaceous glands, and measures $0.4\text{ mm}$ to $0.6\text{ mm}$ thick.

Thin Skin

Skin type covering most of the body that lacks a stratum lucidum, contains sweat glands, hair follicles, and sebaceous glands, and measures $0.075\text{ mm}$ to $0.150\text{ mm}$ thick.

Hemoglobin

An oxygen-binding protein in red blood cells that exhibits a bright red color when bound to oxygen, imparting a reddish tint to dermal blood vessels.

Melanin

A pigment produced and stored in melanocytes occurring in black, brown, tan, and yellow-brown shades.

Carotene

A yellow-orange pigment acquired from yellow-orange vegetables that accumulates in subcutaneous fat and keratinocytes of the stratum corneum and is converted into vitamin A.

Albinism

An inherited recessive condition in which the enzyme required to produce melanin is nonfunctional, resulting in white hair, pale skin, and pink irises.

Nevus

Commonly called a mole; a harmless, localized overgrowth of melanocytes.

Freckles

Yellowish or brown spots representing localized areas of increased melanocyte activity.

Capillary Hemangiomas

Strawberry-colored birthmarks presenting as bright red to deep purple nodules from benign blood vessel tumors that usually disappear during childhood.

Cavernous Hemangiomas

Port-wine stains involving larger dermal blood vessels that may persist for a lifetime.

Friction Ridges

Complex arches and whorls on fingers, palms, soles, and toes formed by large folds and valleys of dermis and epidermis that increase friction upon contact.

Papillary Layer

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

Reticular Layer

The deeper, major region of the dermis composed of dense irregular connective tissue surrounding hair follicles, glands, nerves, and blood vessels.

Lines of Cleavage

Parallel bundles of collagen and elastic fibers aligned along lines of stress that dictate optimal orientation for surgical incisions to speed healing.

Striae

Stretch marks formed when the skin is stretched beyond its capabilities, tearing some collagen fibers in the dermis.

Calcitriol

The active, hormonal form of vitamin D converted in the kidney that increases intestinal absorption of calcium and phosphate.

Transdermal Administration

A method of drug delivery using an adhesive patch where oil-soluble drugs slowly pass through the selectively permeable epidermis into dermal blood vessels.

Vasoconstriction

The narrowing of dermal blood vessel diameters to shunt blood away from the body periphery toward deeper structures in order to conserve heat.

Vasodilation

The enlargement of dermal blood vessel diameters allowing increased blood flow near the skin surface to release body heat.

Nail Plate

The hard structure of a nail comprising the distal free edge, pinkish nail body, and embedded nail root.

Nail Matrix

The actively growing proximal portion of the nail body containing dividing epidermal cells.

Lunula

The whitish, semilunar area located at the proximal end of the nail body.

Eponychium

Also called the cuticle; a narrow band of epidermis extending from the margin of the nail wall onto the nail body.

Hyponychium

The region of thickened stratum corneum underlying the free edge of the nail.

Lanugo

Fine, unpigmented, downy hair that appears on the fetus during the last trimester of development.

Vellus

Fine, primary human hair found over most of the upper and lower limbs.

Terminal Hair

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

Hair Bulb

The swelling at the base of a hair in the dermis that surrounds the connective tissue hair papilla and contains living epithelial cells.

Hair Matrix

Epithelial cells at the base of the hair bulb that actively divide to form new cells that are pushed superficially.

Arrector Pili

Ribbons of smooth muscle extending from the hair follicle to dermal papillae that contract to elevate the hair shaft and cause goosebumps.

Merocrine Sweat Glands

The most numerous, widely distributed simple coiled tubular glands that secrete sweat containing 99\text{\textpercent} water directly onto the skin surface for thermoregulation via exocytosis.

Apocrine Sweat Glands

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

Sebaceous Glands

Holocrine glands that produce an oily, bactericidal lubricant called sebum discharged into hair follicles, stimulated primarily by androgens.

Ceruminous Glands

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

Mammary Glands

Modified apocrine sweat glands in the breast that function exclusively in pregnant and lactating females to produce milk.

Regeneration

The replacement of damaged or dead tissue cells with the exact same cell type, fully restoring organ function.

Fibrosis

The repair process in which fibroblasts fill a gap or wound with collagen scar tissue when original functional tissue cannot be restored.