Integumentary System - Skin Anatomy and Functions (VOCABULARY)

Vocabulary-style flashcards covering skin anatomy, layers, cells, glands, hair, nails, sensory receptors, and functions.

Epidermis

The outer, visible skin layer made of stratified squamous epithelial tissue; avascular and constantly renewing; contains keratinocytes and melanocytes.

Dermis

The middle skin layer beneath the epidermis; contains blood vessels, nerve endings, hair follicles, sweat and oil glands; has papillary and reticular sublayers.

Hypodermis (Subcutis)

The bottom skin layer composed mostly of adipose tissue; insulates, stores energy, cushions, and anchors the skin.

Stratum corneum

Outermost epidermal layer of dead keratinocytes; provides a protective barrier; thick skin has 20–30 layers.

Stratum lucidum

A clear layer of flat, dead keratinocytes found only in thick skin (palms and soles).

Stratum granulosum

Granular epidermal layer with living keratinocytes forming keratin; cells become flatter as they move toward the surface.

Stratum spinosum

Prickle cell layer just above basale; cells appear spiny when dehydrated and interconnect via filaments.

Stratum basale

Deepest epidermal layer; single layer of actively dividing cells that generate new epidermal cells and connect to the dermis.

Keratinocytes

Primary epidermal cells that produce keratin; originate in the basale layer and migrate outward, eventually dying at the surface.

Melanocytes

Pigment-producing cells in the epidermis that synthesize melanin, contributing to skin color and UV protection.

Melanin

Pigment ranging from reddish yellow to brownish black; shields skin from UV radiation; distribution and extent affect color.

Langerhans cells (dendritic cells)

Immune cells in the epidermis that originate in bone marrow and help defend against invaders.

Merkel cells (tactile cells)

Tactile receptors located at the epidermis-dermis boundary; work with nerve endings to sense touch.

Thick skin

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

Thin skin

Most of the body’s skin with four epidermal layers and lacking stratum lucidum.

Papillary layer

Upper dermal layer of areolar connective tissue with dermal papillae that enhance grip and house capillaries.

Dermal papillae

Projections of the papillary layer into the epidermis; create friction ridges (fingerprints) in thick skin.

Friction ridges

Ridges formed by dermal papillae that enhance grip and leave fingerprints.

Reticular layer

Deeper dermal layer of dense irregular connective tissue; houses nerves, vessels, and glands; forms most of the dermis.

Dermaal blood vessels

Vascular network in the dermis that nourishes skin and regulates temperature by vasodilation and vasoconstriction.

Hair (pili)

Keratinized strands growing from hair follicles; provides protection and sensation; growth involves keratinization in the shaft and root.

Hair shaft

Part of the hair that extends above the skin surface; fully keratinized.

Hair root

Part of the hair below the skin surface within the follicle; keratinization is still in progress.

Hair cuticle

Outermost layer of hair shaft composed of overlapping keratinized cells; smooths the hair surface.

Nails

Keratinized plates on fingers and toes; protect digits and assist in manipulation; grow from the nail root.

Nail bed

Skin beneath the nail plate; supports nail growth and health.

Nail root

Growth region of the nail located at the proximal end under the skin.

Cuticle (eponychium)

Fold of skin at the base of the nail; protects the nail matrix.

Sebaceous glands

Oil glands that secrete sebum into hair follicles to soften hair and skin and reduce water loss.

Sebum

Oily substance produced by sebaceous glands that lubricates skin and hair.

Sweat glands (sudoriferous glands)

Glands that produce sweat; distributed as eccrine and apocrine types contributing to temperature regulation and odor.

Eccrine sweat glands

Most numerous sweat glands; simple coiled tubes that secrete watery sweat directly onto the skin surface for thermoregulation.

Apocrine sweat glands

Sweat glands associated with hair follicles in axillary and anogenital regions; produce viscous, lipid-rich sweat linked to body odor.

Vitamin D synthesis

Skin converts UV light into vitamin D; activation occurs in liver and kidneys to form calcitriol for bone health.

UV damage to skin

Ultraviolet radiation can damage elastic fibers, suppress immunity, and increase skin cancer risk; sunscreen mitigates damage.

Tactile receptors

Cutaneous sensory receptors in the skin that detect touch, pressure, and vibration (e.g., tactile and lamellar corpuscles).

Tactile corpuscles

Nerve endings in the dermal papillae that provide light touch sensation.

Lamellar corpuscles

Pressure receptors in the deeper dermis that detect sustained compression.

Cyanosis

Bluish skin color due to low oxygen in blood; indicates poor circulation or respiratory issues.

Jaundice

Yellowing of the skin from bilirubin buildup, usually signaling liver disorder.

Erythema

Reddened skin from fever, inflammation, or allergy due to vascular dilation.

Tattoo basics

Tattoos must deposit pigment into the dermis; epidermal ink removal would fade as epidermal cells shed.

Integumentary system overview

System including skin, hair, nails, sweat glands, and sebaceous glands that protects, senses, and regulates the body.