Chapter 06: Integumentary System

Comprehensive vocabulary flashcards covering the structure, strata, cell types, functions, exocrine glands, clinical pathology, and tissue repair of the integumentary system.

Integument

The body's largest organ, composed of the cutaneous membrane consisting of the superficial epidermis and the deeper dermis.

Epidermis

The superficial, avascular layer of the skin composed of keratinized stratified squamous epithelium.

Dermis

The layer of skin deep to the epidermis, composed of connective tissue containing blood vessels, sweat glands, sebaceous glands, hair follicles, and nerve endings.

Papillary layer

The superficial layer of the dermis composed of areolar connective tissue that forms dermal papillae projecting into the overlying epidermis.

Reticular layer

The deeper, thicker layer of the dermis composed of dense irregular connective tissue surrounding cutaneous structures.

Subcutaneous layer (hypodermis)

A layer deep to the integument composed of areolar and adipose connective tissue that functions in protection, energy storage, and thermal insulation.

Stratum basale

The deepest epidermal layer consisting of a single layer of cuboidal cells attached to the basement membrane that constantly undergo mitosis; contains melanocytes and tactile cells.

Stratum spinosum

An epidermal layer composed of several layers of cells with centrally located oval nuclei and spine-like processes, exhibiting limited mitosis and housing epidermal dendritic cells.

Stratum granulosum

An epidermal layer composed of flat, spindle-shaped cells filled with basophilic keratohyalin granules and shriveled nuclei undergoing keratinization.

Stratum lucidum

A thin, clear epidermal layer found only in thickened areas of skin such as the palms and soles, consisting of densely packed, flattened cells filled with keratin.

Stratum corneum

The most superficial layer of the epidermis, consisting of many layers of flattened, dead, nonnucleated, cornified keratinized cells.

Keratinocytes

The most abundant epidermal cells, responsible for synthesizing keratin to strengthen and water-seal the skin.

Melanocytes

Pigment-producing cells located in the stratum basale that synthesize melanin and transfer it to keratinocytes to protect DNA from ultraviolet radiation.

Epidermal dendritic cells (Langerhans cells)

Immune cells residing in the stratum spinosum that engulf pathogens, alert the immune system, and initiate immune responses.

Tactile cells (Merkel cells)

Sensory receptor cells located in the stratum basale that contact sensory nerve endings and respond to light touch.

Thick skin

Skin covering the palms of the hands and soles of the feet containing all five epidermal strata, including the stratum lucidum; possesses sweat glands but lacks hair follicles and sebaceous glands.

Thin skin

Skin covering most of the body that lacks a stratum lucidum and contains hair follicles, sebaceous glands, and sweat glands.

Hemoglobin

An oxygen-binding protein found in red blood cells that exhibits a bright red color when bound to oxygen, contributing a reddish tint to the skin.

Carotene

A yellow-orange pigment acquired from vegetables that accumulates in keratinocytes of the stratum corneum and subcutaneous fat.

Nevus

A mole; a harmless, localized overgrowth of melanocytes that should be monitored for changes suggesting malignancy.

Freckles

Yellowish or brown skin spots resulting from localized areas of increased melanocyte activity rather than increased cell numbers.

Hemangioma

A skin discoloration resulting from a benign proliferation of blood vessels.

Friction ridges

Folds and valleys of the dermis and epidermis on the fingers, palms, and soles that form unique patterns (such as arches, whorls, loops, and combinations) to enhance friction and grip.

Cleavage lines

Predominant orientations of collagen fiber bundles in the dermis; incisions parallel to these lines heal rapidly with minimal scarring, whereas perpendicular incisions gape open.

Calcitriol

The active hormonal form of vitamin $D_3$ that regulates blood calcium levels by increasing dietary absorption of calcium and phosphate in the small intestine.

Lanugo

Fine, unpigmented, downy hair that develops on the fetus during the third trimester of pregnancy.

Vellus

Fine, lightly pigmented hair that forms the primary hair covering the human body, particularly on the upper and lower limbs.

Terminal hair

Coarse, pigmented, longer hair found on the scalp, eyebrows, and eyelashes, and replacing vellus hair in axillary and pubic regions during puberty.

Exocrine gland secretion types

Classification of glands based on release mechanisms: merocrine glands release vesicles via exocytosis, apocrine glands pinch off the apical cellular cytoplasm, and holocrine glands shed whole disintegrating cells.

Granulation tissue

Vascular connective tissue formed during step 3 of cutaneous repair, characterized by proliferating fibroblasts and inward budding of regrowing capillary blood vessels.

Wound healing intentions

Surgical wound healing categories: primary intention involves early suturing of a clean incision to produce a hairline scar; secondary intention involves granulation tissue filling an open gaping wound; tertiary intention involves delayed suturing with a wide scar.

Burn classifications

Degrees of burn depth: first-degree burns affect only the epidermis (redness, pain); second-degree burns damage the epidermis and part of the dermis (blistering); third-degree burns destroy all layers through the subcutaneous tissue.

Rule of Nines

A clinical estimation tool dividing the adult surface area into regions of $9\%$ or multiples of $9\%$ (head/neck $9\%$, each upper limb $9\%$, anterior trunk $18\%$, posterior trunk $18\%$, each lower limb $18\%$, and perineum $1\%$) to estimate burn severity.

Basal cell carcinoma

The most common and least dangerous skin cancer, originating in the stratum basale and presenting as a small, pearly elevation with a central depression, commonly on the face.

Squamous cell carcinoma

Skin cancer originating from keratinocytes of the stratum spinosum, presenting as raised, reddened, scaly lesions on the scalp, ears, lips, or back of hands that can metastasize.

Malignant melanoma

The most lethal form of skin cancer arising from melanocytes, typically in a preexisting mole, marked by rapid aggressive growth and high metastatic potential.

ABCDE rule

Clinical guidelines for detecting melanoma: Asymmetry, Border irregularity, Color unevenness, Diameter greater than $6\,\text{mm}$, and Evolving shape, size, or symptoms.