Integumentary System Practice Flashcards

Vocabulary practice flashcards covering the structure, layers, accessory structures, physiological functions, and pathological conditions of the integumentary system based on lecture notes.

Integumentary System

The organ system providing overall protection to the body, composed of the skin and its accessory structures, including hair, nails, sweat glands, and sebaceous glands.

Keratinocyte

A cell that manufactures and stores the protein keratin, making up all epithelial layers of the epidermis except the stratum basale.

Keratin

An intracellular fibrous protein that gives hair, nails, and skin their hardness and water-resistant properties.

Stratum Basale

The deepest layer of the epidermis that attaches to the basal lamina, containing a single layer of cuboidal stem cells known as basal cells.

Basal Cell

A cuboidal-shaped stem cell located in the stratum basale that serves as the precursor for all epidermal keratinocytes.

Dermal Papilla

A finger-like projection in the superficial portion of the dermis that extends into the stratum basale to strengthen the connection between the epidermis and dermis.

Merkel Cell

A specialized receptor cell dispersed in the stratum basale responsible for stimulating sensory nerves that the brain perceives as touch.

Melanocyte

A pigment-producing cell scattered in the stratum basale that synthesizes melanin to color skin and hair and protect epidermal cells from UV damage.

Melanin

A pigment produced by melanocytes in two primary forms—eumelanin (black/brown) and pheomelanin (red)—that absorbs ultraviolet radiation.

Thick Skin

Skin found exclusively on the palms of the hands and soles of the feet that contains a fifth epidermal layer called the stratum lucidum.

Stratum Spinosum

An epidermal layer composed of $8$ to $10$ layers of keratinocytes connected by desmosomes, giving cells a spiny appearance under histological preparation.

Langerhans Cell

A type of dendritic cell in the stratum spinosum that functions as a macrophage by engulfing bacteria, foreign particles, and damaged cells.

Stratum Granulosum

An epidermal layer $3$ to $5$ layers deep with a grainy appearance due to the accumulation of fibrous keratin and keratohyalin granules.

Keratohyalin

A protein in the stratum granulosum that accumulates as lamellar granules to aggregate, cross-link, and bundle keratin precursors.

Stratum Lucidum

A smooth, translucent layer of the epidermis located between the stratum granulosum and stratum corneum, found only in thick skin.

Eleidin

A clear, clear-derived protein from keratohyalin that fills dead, flattened keratinocytes in the stratum lucidum to give them a transparent appearance.

Stratum Corneum

The most superficial layer of the epidermis, composed of $15$ to $30$ layers of dead, cornified cells that prevent dehydration and microbial penetration.

Dermis

The core layer of the integumentary system containing blood and lymph vessels, nerves, hair follicles, and sweat glands made of loose and dense connective tissue.

Papillary Layer

The superficial dermal layer composed of loose, areolar connective tissue containing dermal papillae, fibroblasts, adipocytes, phagocytes, and Meissner corpuscles.

Reticular Layer

The deep, thick dermal layer composed of dense irregular connective tissue featuring a tight meshwork of collagen and elastin fibers.

Hypodermis

The subcutaneous layer directly beneath the dermis consisting of loose areolar connective tissue and adipose tissue that provides insulation, cushioning, and fat storage.

Melanosome

A cellular vesicle used by melanocytes to transfer synthesized melanin pigment into surrounding keratinocytes.

Albinism

A genetic disorder characterized by the complete or partial lack of melanin production in melanocytes, affecting the coloration of skin, hair, and eyes.

Vitiligo

A skin condition where melanocytes in certain areas lose the ability to produce melanin, resulting in depigmented lighter patches of skin.

Cyanosis

A condition in which the skin turns blue due to prolonged oxygen reduction and the dominance of dark red deoxyhemoglobin in the blood.

Hair Follicle

An epidermal penetration of the dermis from which individual strands of hair originate.

Hair Matrix

A layer of mitotically active basal cells located within the hair bulb that divides to produce cells forming the hair root and shaft.

Arrector Pili

A smooth muscle attached to each hair root that contracts in response to sympathetic nerve signals, causing the hair shaft to stand upright.

Anagen Phase

The active growth phase of hair during which basal cells divide rapidly, lasting typically from $2$ to $7\text{ years}$ with hair growing at approximately $0.3\text{ mm/day}$.

Catagen Phase

The transitional phase of hair growth lasting $2$ to $3\text{ weeks}$ that marks the end of active hair follicle growth.

Telogen Phase

The resting phase of the hair follicle growth cycle lasting $2$ to $4\text{ months}$ before new basal cells initiate another anagen phase.

Nail Body

A dense structure of dead keratinocytes formed on the nail bed that protects the digits from mechanical stress and provides back-support for picking up objects.

Eponychium

The nail fold that meets the proximal end of the nail body, commonly referred to as the cuticle.

Lunula

The crescent-shaped region at the base of the nail body created by a thick layer of underlying epithelium over the nail matrix.

Eccrine Sweat Gland

A coiled merocrine gland in the dermis that secretes hypotonic sweat consisting mainly of water, salt, antibodies, and dermcidin for thermoregulation.

Apocrine Sweat Gland

A large sweat gland associated with hair follicles in hairy regions (armpits, genitals) that secretes organic compounds subject to bacterial decomposition and odor.

Sebaceous Gland

An oil gland associated with hair follicles that secretes sebum to lubricate and waterproof the skin and hair.

Sebum

A lipid mixture excreted onto the skin surface by sebaceous glands that keeps the stratum corneum pliable and possesses antibacterial properties.

Meissner Corpuscle

A tactile receptor located in the dermal papillae that responds to light touch.

Pacinian Corpuscle

A lamellated sensory receptor located in the skin that senses vibration.

Insensible Perspiration

The unnoticeable, baseline secretion of approximately $500\text{ mL}$ of sweat per day produced for body temperature regulation.

Cholecalciferol

A form of vitamin $D_3$ synthesized in the epidermal layer of the skin from a derivative of cholesterol upon exposure to ultraviolet radiation.

Rickets

A condition in children caused by vitamin D deficiency leading to misshapen, poorly mineralized bones and bowleggedness.

Osteomalacia

A softening of the bones occurring in elderly or adult individuals due to insufficient vitamin D and impaired calcium absorption.

Basal Cell Carcinoma

The most common form of skin cancer, arising from mitotically active stem cells in the stratum basale of the epidermis.

Squamous Cell Carcinoma

A skin cancer affecting keratinocytes in the stratum spinosum that presents as lesions commonly found on the scalp, ears, and hands.

Melanoma

A highly metastatic and fatal skin cancer characterized by uncontrolled growth of melanocytes, often diagnosed using the ABCDE mnemonic and featuring lesions larger than $6\text{ mm}$.

Eczema

An inflammatory skin condition that manifests as dry, red, itchy patches resembling rashes, often managed with moisturizers and corticosteroids.

Acne

A skin disturbance occurring in regions rich in sebaceous glands where excess sebum and keratin block hair follicles, leading to bacterial infection.

First-Degree Burn

A superficial burn affecting only the epidermis, causing pain and swelling, which typically heals independently within a few days.

Second-Degree Burn

A burn extending into both the epidermis and a portion of the dermis, resulting in painful skin blistering and swelling.

Third-Degree Burn

A full-thickness burn extending completely through the epidermis and dermis, destroying nerve endings and sensory function.

Fourth-Degree Burn

A severe burn that destroys the full thickness of the skin and damages underlying muscle and bone tissue.

Rule of Nines

A clinical calculation system that assigns body anatomical regions percentage factors of 9 to estimate total burn surface area.

Keloid

A raised, hypertrophic scar resulting from the excessive overproduction of collagen tissue during wound healing.

Bedsores

Decubitus ulcers caused by constant, unrelieved pressure over bony body parts, leading to reduced blood flow and tissue necrosis.