Integumentary System Study Guide

Comprehensive vocabulary flashcards covering the Integumentary System study guide, including epidermal and dermal layers, cutaneous cells, skin glands, burn classifications, skin pigments, hair anatomy, and clinical conditions.

Rule of nines

A clinical tool used to determine the percentage of body surface area burned and estimate volume of fluid loss; allocated as $9\%$ for anterior and posterior head and neck, $18\%$ for anterior and posterior upper limbs ($4\frac{1}{2}\%$ per side), $36\%$ for anterior and posterior trunk ($18\%$ anterior trunk), $1\%$ for the perineum, and $36\%$ for anterior and posterior lower limbs ($9\%$ per anterior lower limb).

Layers and appendages of the skin

The structural anatomy of the skin consisting of the superficial epidermis, the underlying dermis (divided into the papillary layer and reticular layer), the hypodermis (subcutaneous tissue; not part of skin), sensory and nervous structures (free nerve endings, lamellar corpuscle, root hair plexus), and appendages (hair shaft, hair root, hair follicle, arrector pili muscle, sebaceous gland, and eccrine sweat gland).

Sudoriferous glands

The anatomical term for sweat glands, categorized into eccrine (merocrine) and apocrine types.

Eccrine (merocrine) glands

Sweat glands located on the palms, soles, and forehead whose primary function is thermoregulation.

Apocrine glands

Sweat glands found primarily in the axillary and anogenital areas; their exact function is unknown, but they may produce sexual scent.

Papillary layer

The superficial layer of the dermis composed of connective tissue containing epidermal ridges, which are collectively called friction ridges.

Reticular layer

The deeper layer making up $80\%$ of dermal thickness; composed of coarse, dense fibrous connective tissue with elastic fibers, collagen for strength and resiliency, cleavage lines, flexure lines (dermal folds), and the cutaneous plexus of blood vessels located between it and the hypodermis.

First-degree burn ($1^{\text{st}}$ degree)

A partial-thickness burn causing epidermal damage only, characterized by redness, edema, and pain.

Second-degree burn ($2^{\text{nd}}$ degree)

A partial-thickness burn that involves both epidermal and dermal damage.

Third-degree burn ($3^{\text{rd}}$ degree)

A full-thickness burn presenting as gray-white, cherry red, or blackened skin in which nerve endings are destroyed, requiring skin grafting for treatment.

Nail bed

The region of epidermis situated underneath the keratinized nail plate, given its pink appearance by underlying capillaries.

Eponychium

The nail fold that projects directly onto the surface of the nail body.

Hyponychium

The area located under the free edge of the nail plate where dirt typically accumulates.

Vernix caseosa

A sebaceous gland secretion that shields and protects the skin of a fetus while submerged in watery amniotic fluid.

Cyanosis

A bluish discoloration of the skin caused by a deficiency or lack of oxygen ($\text{O}_2$).

Erythema

Redness of the skin associated with embarrassment, fever, hypertension, inflammation, or allergy.

Pallor

Paleness of the skin that can result from anger, fear, anemia, or low blood pressure.

Jaundice

Yellow discoloration of the skin indicating a liver disorder.

Bronzing

A bronze or metallic coloration of the skin associated with Addison's disease.

Bruises

Black and blue skin hues caused by clotted blood pooled beneath the skin.

Basal cell carcinoma

A form of skin cancer where the cells of the basal layer (stratum basale) are affected.

Squamous cell carcinoma

A form of skin cancer that involves the keratinocytes of the stratum spinosum.

Melanoma

The most deadly form of skin cancer, which involves and originates from the melanocytes.

UV radiation

Exposure to ultraviolet radiation or light, which serves as the most important risk factor leading to skin cancer.

Stratum basale (Basal layer)

The deepest epidermal layer where active mitotic cell division takes place.

Stratum spinosum

The layer of the epidermis where keratinocytes look spiky, containing abundant melanosomes and dendritic cells.

Stratum granulosum

The epidermal layer containing water-resistant lamellar granules, where cells begin to disintegrate.

Stratum lucidum

The epidermal layer found exclusively in thick skin.

Stratum corneum

The most superficial epidermal layer composed of stratified squamous cells that slough off (shed), accounting for three-quarters ($\frac{3}{4}$) of the total epidermal thickness.

Body temperature regulation (vascular response)

A homeostatic mechanism where dermal blood vessels constrict in cold environments to conserve heat and dilate in hot environments to dissipate heat.

Melanin

Pigment produced by melanocytes and packaged into melanosomes, which are sent to keratinocytes to shield cellular DNA from harmful UV radiation.

Hair shaft regions

The three concentric structural regions comprising a hair shaft: the inner medulla, the surrounding cortex, and the outer cuticle.

Dendritic cells (Langerhans cells)

Star-shaped macrophages patrolling the deep epidermis that activate the immune system through phagocytosis.

Tactile cells (Merkel cells)

Specialized sensory receptor cells in the epidermis that provide the sensation of touch and pressure.

Lamellated corpuscle

A deeper cutaneous sensory structure responsible for detecting pressure sensation.

Alopecia areata

A specific form of alopecia (hair loss) caused by an immune system disorder.

Ceruminous glands

Modified cutaneous glands that produce earwax.

Dermal cells

The primary cell types populating the dermis, including fibroblasts, macrophages, mast cells, and white blood cells (WBCs).

Desmosomes

Cellular junctions that connect adjacent cells together and allow cells to maintain flexibility at their connection points.

Cutaneous infection barriers

The multi-faceted defense mechanisms of the skin against infection, including antimicrobial defensins, tight junctions that block pathogen entry, and stratified keratinocyte layers.

Cleavage (tension) lines

Lines of tension in the reticular dermis; surgical incisions made parallel to these lines heal more readily and result in limited scarring.

Keratin

A fibrous structural protein synthesized in the epidermis responsible for the protective toughening of the skin.

Apoptosis

A regulated process of programmed, controlled cell death.

Striae

Dermal scars left behind following extreme stretching of the skin.

Vellus

The pale, fine body hair typically found on children and adult females.

Hair root

The portion of the hair embedded within the scalp where active keratinization is ongoing.

Arrector pili

A small band of smooth muscle attached to the hair follicle that contracts to pull the hair upright.

Hair papilla

A nipple-like bit of dermal tissue containing a knot of capillaries that supplies essential nutrients to growing hair.

Hair matrix

The actively dividing germinal layer of cells in the hair bulb that generates new hair cells.