Integumentary System Lecture Notes

These flashcards cover the anatomy, layers, cell types, functions, and clinical conditions of the integumentary system based on the provided lecture transcript.

Integumentary System

The collective name for the skin and its accessory structures, which include hair, nails, glands, and sensory receptors.

Cutaneous membrane

Another name for the skin, which is the largest organ of the body by weight.

Epidermis

The outer epithelial layer of the skin, composed of stratified squamous epithelium and lacking blood vessels.

Dermis

The inner layer of skin composed of dense irregular connective tissue, including collagenous and elastic fibers, muscle, blood, and nervous tissue.

Subcutaneous layer (hypodermis)

An insulating layer beneath the dermis composed of areolar and adipose connective tissue; it is not considered part of the skin.

Keratinization

The process of hardening, dehydration, and keratin accumulation that occurs in epidermal cells as they migrate toward the surface.

Keratin

A tough, fibrous, and waterproof protein produced and stored in epidermal cells.

Stratum Basale

The deepest layer of the epidermis, consisting of a single layer of cuboidal to low columnar cells attached to the basement membrane.

Melanocytes

Specialized cells in the stratum basale that produce the pigment melanin to absorb UV light and prevent DNA damage.

Melanosomes

Melanin granules transferred from melanocytes to keratinocytes via cytoplasmic processes.

Merkel (Tactile) cells

Epidermal cells located in the stratum basale that are sensitive to fine touch.

Stratum Spinosum

The "spiny layer" of the epidermis consisting of several layers of polygonal keratinocytes attached by desmosomes.

Dendritic (Langerhans) cells

Immune cells found in the stratum spinosum that act as phagocytes to fight infection and initiate immune responses.

Stratum Granulosum

A layer of three to five layers of keratinocytes where keratinization begins and organelles start to degrade.

Stratum Lucidum

A thin, translucent region of two to three cell layers found only in thick skin, such as the palms and soles.

Stratum Corneum

The most superficial "hornlike layer" of the epidermis, composed of $20$ to $30$ layers of dead, anucleate, scaly keratinized cells called corneocytes.

Eumelanin

A brownish or black pigment found in the epidermis and hair.

Pheomelanin

A reddish-yellow pigment found in certain areas such as the lips and in hair.

Albinism

An inherited mutation in melanin genes resulting in a lack of melanin and nonpigmented skin.

Basal cell carcinoma

The most common type of skin cancer, arising from the cells of the stratum basale.

Squamous cell carcinoma

A type of skin cancer arising from the cells of the stratum spinosum; it may bleed and has a varied appearance.

Melanoma

The most deadly form of skin cancer, arising from melanocytes; it accounts for $4\%$ of cases but $80\%$ of skin cancer deaths.

ABCDE Rule

A clinical guide for signs of melanoma: Asymmetry, Border irregularity, Color not uniform, Diameter greater than $6\,mm$, and Evolving or changing.

Dermal papillae

Projections between epidermal ridges that bind the epidermis to underlying tissues and forming fingerprints.

Tactile (Meissner’s) corpuscles

Sensory receptors located in the dermis that are sensitive to light touch.

Lamellated (Pacinian) corpuscles

Sensory receptors located in the dermis that are sensitive to pressure.

Papillary layer

The thinner, superficial layer of the dermis composed of areolar connective tissue.

Reticular layer

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

Nail matrix

The active growth region of the nail located at the proximal end of the nail bed.

Lunula

The pale, half-moon-shaped region at the base of the nail that lies over the nail matrix.

Arrector pili muscle

A muscle attached to a hair follicle that contracts in response to cold or fear, causing goosebumps.

Sebaceous glands

Holocrine glands usually associated with hair follicles that produce sebum to keep hair and skin soft and waterproof.

Sebum

A fatty material and cellular debris produced by sebaceous glands.

Eccrine (merocrine) sweat glands

The most numerous sweat glands that respond to elevated body temperature by secreting a fluid primarily composed of water.

Apocrine sweat glands

Sweat glands found in axillary and groin areas that respond to emotions and pain; their secretions develop odors.

Ceruminous glands

Modified sweat glands in the external acoustic meatus that secrete ear wax.

Hypothalamus

The part of the brain that monitors the body's temperature set point, which is approximately $37^\circ\text{C}$ ($98.6^\circ\text{F}$).

Vasodilation

The widening of dermal blood vessels to allow more blood to flow to the surface to release heat when body temperature rises.

Vasoconstriction

The narrowing of dermal blood vessels to reduce blood flow to the surface and conserve heat when body temperature falls.

Inflammation

A normal response to injury where blood vessels dilate and become more permeable, causing redness, swelling, warmth, and pain.

Fibroblasts

Cells that secrete collagen fibers to bind the edges of a deep wound together during healing.

Superficial, partial-thickness burn

A first-degree burn that injures only the epidermis, characterized by redness and heat without scarring.

Deep, partial-thickness burn

A second-degree burn that destroys the epidermis and some dermis, often characterized by blisters.

Full-thickness burn

A third-degree burn that destroys the epidermis, dermis, and accessory structures; it often requires skin grafts.

Rule of Nines

A method that divides the body surface into regions of $9\%$ or multiples of $9\%$ to estimate the extent of burn injuries.

Androgenic alopecia

Pattern baldness associated with lowered levels of testosterone in men or estrogen in women.

Alopecia areata

An autoimmune disorder where the body produces antibodies that attack hair follicles, causing hair loss.

Acne vulgaris

A disorder of the sebaceous glands common at puberty, where glands become clogged with extra sebum and epithelial cells.