Chapter 5 (Part II): The Integumentary System - Accessory Structures, Repair, and Burns

Vocabulary practice flashcards covering accessory organs of the skin (hair, glands, nails), skin injury repair phases, burn classifications, and age-related integumentary changes.

Hair

A nonliving, long, cylindrical accessory structure produced inside a hair follicle that originates in the dermis and projects through the epidermis.

Root hair plexus

Sensory nerves surrounding the base of a hair follicle that detect movement of the hair shaft.

Arrector pili muscle

A bundle of involuntary smooth muscle attached to a hair follicle whose contraction pulls the hair upright, producing "goose bumps."

Hair root

The portion of the hair that anchors it into the skin, beginning at the hair bulb and extending roughly halfway to the skin surface.

Hair shaft

The nonliving portion of the hair extending from the end of the hair root to form the visible, protruding structure above the skin surface.

Medulla (hair)

The central core of a hair strand that contains flexible soft keratin.

Cortex (hair)

The intermediate layer of a hair strand containing thick layers of hard keratin that give hair its stiffness.

Cuticle (hair)

The thin, tough surface layer of a hair strand composed of hard keratin.

Internal root sheath

A follicular layer surrounding the hair root and deeper shaft whose cells disintegrate quickly, preventing it from spanning the full length of the follicle.

External root sheath

The hair follicle layer extending from the skin surface down to the hair matrix.

Glassy membrane

A thickened, clear basement membrane layer wrapped by the dense connective tissue sheath of the hair follicle.

Hair bulb

The enlarged epithelial base of the hair follicle surrounding the hair papilla where hair production begins.

Hair papilla

A peg of connective tissue at the base of the hair bulb containing capillaries and nerves essential for nourishing growing hair cells.

Hair matrix

A layer of basal epithelial cells at the base of the hair bulb that actively divides to generate new hair cells.

Club hair

An inactive hair formed at the end of a hair growth cycle when the follicle stops dividing; it is eventually shed when a new growth cycle begins.

Vellus hairs

Fine, soft, nonpigmented hairs that cover most of the body surface.

Terminal hairs

Heavy, pigmented, coarse hairs found on the head, eyebrows, eyelashes, and developing in the axillary and pubic regions after puberty.

Sebaceous glands

Simple branched alveolar holocrine oil glands that secrete sebum into hair follicles to lubricate and protect hair shafts and condition the skin.

Sebum

An oily lipid secretion produced by sebaceous glands that lubricates keratinized structures, conditions skin, and inhibits bacterial growth.

Seborrheic dermatitis

An inflammatory skin condition caused by abnormally overactive sebaceous glands.

Sebaceous follicles

Large sebaceous glands that discharge sebum directly onto the skin surface rather than into a follicle, located on the face, back, chest, nipples, and external genitalia.

Apocrine sweat glands

Coiled tubular glands found in the axillae, pubic regions, and areolae that release a cloudy, sticky, nutrient-rich secretion into hair follicles via merocrine mechanisms beginning at puberty.

Myoepithelial cells

Contractile epithelial cells situated between secretory cells and the basement membrane in sweat glands that squeeze out secretions in response to autonomic or hormonal signals.

Eccrine (merocrine) sweat glands

Widely distributed coiled tubular sweat glands that discharge a watery fluid directly onto the skin surface to lower body temperature and excrete waste.

Sensible perspiration

The clear, watery secretion produced primarily by eccrine glands consisting predominantly of water, sodium chloride, electrolytes, and metabolic wastes.

Ceruminous glands

Modified sweat glands in the external ear canal that secrete cerumen (earwax) to trap foreign matter and protect the eardrum.

Nail body

The visible keratinized portion of the nail that rests directly on the nail bed.

Hyponychium

A thickened region of stratum corneum located directly beneath the free distal edge of the nail.

Nail root

An epidermal fold embedded deep in the dermis where epithelial division and nail production occur.

Eponychium

A narrow fold of stratum corneum extending from the nail root over the base of the exposed nail body; commonly called the cuticle.

Lunula

The pale, crescent-shaped area at the proximal base of the nail body where underlying blood vessels are obscured.

Inflammatory phase

The initial phase of integumentary injury repair where bleeding occurs and local mast cells release chemicals that induce vasodilation, swelling, and pain.

Migration phase

The second phase of injury repair occurring several hours post-injury, characterized by scab formation, stratum basale cell migration, macrophage phagocytosis, and granulation tissue emergence.

Granulation tissue

The combination of the fibrin blood clot, proliferated fibroblasts, and newly formed capillary networks that fills a healing wound during the migration phase.

Proliferation phase

The healing phase occurring approximately one week post-injury, marked by dissolution of the clot, extensive collagen fiber meshwork production by fibroblasts, and migration of epidermal cells underneath the scab.

Scarring phase

The final stage of injury repair where the scab is shed, the epidermis is restored, and dense fibrous scar tissue produced by fibroblasts fills the dermal injury site.

Keloid

A thick, raised mass of excessive fibrous scar tissue covered by a smooth, shiny epidermis, occurring more commonly in individuals with dark skin.

First-degree burn

A partial-thickness burn restricted to the superficial epidermis that causes localized inflammation, redness, and minor pain without blistering.

Second-degree burn

A partial-thickness burn that destroys the entire epidermis and penetrates into the dermis, causing blistering, swelling, and severe pain.

Third-degree burn

A full-thickness burn extending through the epidermis and dermis into the subcutaneous layer; it destroys nerve endings, glands, and hair follicles, and cannot re-epithelialize without skin grafts.

Rule of nines

A clinical estimation method for adults where body surface area is subdivided into multiples of nine: head ($9\%$), each upper limb ($9\%$), trunk ($36\%$), each lower limb ($18\%$), and genitalia ($1\%$).