Integumentary System Flash Cards

Integumentary system

Organ system consisting of the skin, hair, nails, and cutaneous glands.

Two main layers of the skin

Epidermis and dermis.

Hypodermis relationship to skin

Not technically part of the skin; lies deep to the dermis and connects skin to deeper tissues.

Epidermis

The outer, avascular layer of skin made of keratinized stratified squamous epithelium.

Five epidermal strata (superficial to deep)

Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale.

Mnemonic for epidermal strata (superficial to deep)

Come Let’s Get Sun Burned: Corneum, Lucidum, Granulosum, Spinosum, Basale.

Stratum corneum

Outermost layer made of dead, flattened, keratinized cells; protective and continuously shed.

Stratum lucidum

Clear epidermal layer found only in thick skin of palms and soles.

Stratum granulosum

Layer where keratinization increases and cells flatten and begin dying.

Stratum spinosum

Several layers of keratinocytes; contains dendritic immune cells.

Stratum basale

Deepest epidermal layer; mitotically active basal cells produce new keratinocytes; contains melanocytes and Merkel cells.

Epidermal layer absent in thin skin

Stratum lucidum.

Dermis

Connective-tissue layer beneath epidermis containing vessels, nerves, receptors, follicles, and glands.

Two layers of the dermis

Papillary and reticular layers.

Papillary layer

Superficial ~$20\%$ of dermis; areolar connective tissue with dermal papillae, capillaries, and sensory structures.

Reticular layer

Deep ~$80\%$ of dermis; dense irregular connective tissue with collagen/elastic fibers, vessels, nerves, follicles, and glands.

Hypodermis

Adipose/areolar layer deep to dermis that cushions, insulates, stores energy, and anchors skin.

Keratin

Tough protective, water-resistant structural protein in skin, hair, and nails.

Melanin

Pigment made by melanocytes that contributes to skin/hair color and helps protect against UV.

Carotene

Yellow/orange pigment contributing to skin color.

Contribution of hemoglobin to skin color

Blood pigment that contributes red/pink tones to skin.

Albinism

Inherited condition characterized by reduced or absent melanin production.

Vitiligo

Patchy loss of melanocytes causing depigmented skin.

Erythema

Redness of skin caused by increased blood flow.

Pallor

Unusual paleness of skin, often from reduced blood flow or reduced hemoglobin.

Jaundice

Yellow skin discoloration caused by bilirubin accumulation.

Cyanosis

Bluish/gray skin discoloration associated with inadequate blood oxygenation.

Skin manifestation of Addison’s disease

Increased pigmentation/hyperpigmentation.

Hair follicle

Inward epidermal extension into dermis that surrounds the hair root.

Hair shaft

Part of hair projecting above the skin surface.

Hair root

Part of hair below the skin within the follicle.

Hair bulb

Enlarged base of the hair root in the deeper dermis.

Hair matrix

Growth zone in hair bulb containing mitotically active cells.

Hair papilla

Connective-tissue projection in hair bulb containing blood vessels and nerves.

Hair medulla

Central core of the hair.

Hair cortex

Layer surrounding medulla; forms most of the hair.

Hair cuticle

Hard keratinized outer layer of hair.

Primary determinant of hair color

Melanin.

Arrector pili

Tiny smooth muscle that pulls hair upright and causes goose bumps.

Vellus hair

Fine, pale body hair.

Terminal hair

Coarse, more pigmented hair such as scalp and eyebrow hair.

Anagen phase

Active hair growth phase.

Catagen phase

Short transitional/regressive hair phase.

Telogen phase

Resting hair phase.

Nail body/plate

Visible hard keratinized nail that rests on nail bed.

Nail bed

Skin beneath the nail body.

Nail root

Proximal hidden portion of the nail.

Nail matrix

Growth region where proliferating basal cells produce the nail.

Nail fold

Skin overlapping the nail edges and helping anchor it.

Eponychium

Cuticle/proximal nail fold at the base of the nail.

Lunula

Pale crescent-shaped area at the nail base.

Hyponychium

Thickened skin beneath the free edge of the nail.

Sudoriferous glands

Sweat glands.

Eccrine gland

Sweat gland opening directly onto skin; secretes watery sweat; important for thermoregulation.

Apocrine gland

Sweat gland in axillary/anogenital areas that usually empties into hair follicles and becomes active at puberty.

Ceruminous gland

Modified apocrine gland in ear canal that produces earwax.

Sebaceous gland

Holocrine oil gland producing sebum that lubricates/waterproofs skin and hair.

Locations where sebaceous glands are absent

Palms and soles.

Main functions of skin

Protection, sensation, thermoregulation, vitamin D synthesis, blood reservoir, and excretion.

Meissner corpuscle

Cutaneous receptor associated with light touch.

Pacinian corpuscle

Cutaneous receptor associated with deep pressure and vibration.

Skin mechanisms for cooling the body

Sweating and vasodilation increase heat loss.

Skin mechanism for heat conservation

Vasoconstriction reduces heat loss.

Basal cell carcinoma

Most common skin cancer; begins in stratum basale; usually slow-growing and highly treatable when caught early.

Squamous cell carcinoma

Cancer of keratinocytes, associated with stratum spinosum; more likely to metastasize than basal cell carcinoma.

Malignant melanoma

Cancer of melanocytes; most dangerous major skin cancer because it can spread rapidly.

ABCDE melanoma rule

Asymmetry, Border irregularity, Color variation, Diameter, Evolving.

Purpose of the Rule of Nines

Estimating percentage of total body surface area affected by burns.

Rule of Nines percentage: Adult head and neck

$$9\%$$

Rule of Nines percentage: Each adult arm

$$9\%$$

Rule of Nines percentage: Anterior trunk

$$18\%$$

Rule of Nines percentage: Posterior trunk

$$18\%$$

Rule of Nines percentage: Each adult leg

$$18\%$$

Rule of Nines percentage: Perineum/genital region

$$1\%$$

First-degree burn

Burn affecting epidermis only; red and painful; no blisters; skin remains intact.

Second-degree burn

Burn affecting epidermis plus part of dermis; painful/tender with blisters.

Third-degree burn

Full-thickness destruction of epidermis and dermis; may be white/red/brown/black and may be painless centrally due to nerve destruction.

Fourth-degree burn

Burn extending beyond skin into deeper tissues such as muscle and/or bone.

Eczema

Inflammatory condition causing dry, itchy, irritated skin.

Acne

Inflammation/plugging of hair follicles and sebaceous glands involving sebum, keratin, bacteria, and inflammation.

Scar

Fibrous connective tissue replacing normal tissue after deeper injury.

Keloid

Excessive scar tissue extending beyond the original wound.

Bedsore (decubitus ulcer)

Pressure injury caused by prolonged compression and reduced blood flow.

Stretch mark

Dermal tearing/scarring from rapid skin stretching.

Callus

Broad thickened epidermis from repeated pressure/friction.

Corn

Localized thickened skin from repeated pressure/friction, often on feet.