Integumentary System, Cutaneous Structures, Glands, and Wound Healing

Comprehensive practice flashcards covering integumentary system anatomy, epidermal/dermal layers, skin pigments, hair structures, cutaneous glands, and wound healing stages.

What are the key characteristics and cell features of the stratum corneum?

It is the most superficial layer of the epidermis consisting of rows of fused, flattened, dead cells filled with keratin (known as cornified or horny cells) that desquamate (shed) and are continuously replaced.

How are epidermal ridges formed and what is their clinical/forensic significance on the palms and soles?

Epidermal ridges are formed on the outer epidermal surface as a result of dermal contours. On the palms and soles, they form unique patterns of loops and whorls specific to each individual, creating fingerprints while increasing friction and surface area.

How does the epidermis receive nourishment given that it is avascular?

Nourishment occurs via diffusion from the capillary bed of the dermis, which is only sufficient for epidermal cells located close to the dermis; more superficial cells die as a result.

What is the dermal origin and basic composition of the dermis?

Located deep to the stratum basale, the dermis develops from embryonic mesoderm and consists of dense irregular connective tissue containing blood vessels, nerves, and accessory structures such as hair follicles and glands.

What are dermal papillae and where are they located?

Dermal papillae are projections from the thin, outer papillary layer of the dermis that protrude into the epidermal region, creating epidermal ridges and housing capillary loops as well as temperature and pressure receptors.

What causes striae (stretch marks) and lines of cleavage in the reticular layer of the dermis?

Striae occur when skin stretch exceeds the elastic fibers' ability to stretch, tearing dermal tissue and blood vessels to form white scars. Lines of cleavage represent parallel bundles of collagen and elastic fibers along which skin heals best when cut in parallel.

What is the hypodermis and what are its main functions?

Also called subcutaneous tissue or superficial fascia, it consists of loose connective tissue and adipose tissue. It attaches skin to underlying structures, pads the body, serves as an energy reserve, insulates, and is highly vascular for drug administration.

What three major factors determine skin color?

1) Melanin (yellow to dark brown pigment), 2) Carotene (yellowish pigment and precursor to Vitamin A), and 3) The amount of blood in dermal capillaries along with the oxygenation state of hemoglobin.

How do melanin production and melanocyte numbers vary between individuals?

The number of melanocytes is constant between different individuals irrespective of race, but darker and more abundant melanin is produced in darker individuals.

What is the difference between albinism and vitiligo?

Albinism is a genetic lack of melanin synthesis, whereas vitiligo is characterized by a localized loss of melanocytes in specific areas of the skin.

What three concentric layers make up the cross-section of a hair root and shaft?

1) Medulla: the central core containing pigment granules. 2) Cortex: keratinized cells surrounding the medulla. 3) Cuticle: hard, keratinized cells forming the outermost layer.

What are the roles of the hair papilla and hair matrix?

The hair papilla is dermal connective tissue containing blood vessels that nourish the follicle. The hair matrix consists of mitotically active cells arising from the stratum basale covering the papilla that produce the medulla, cortex, and cuticle.

What are the three distinct types of human hair?

1) Lanugo: fine hair present on a fetus. 2) Vellus: fine 'peach fuzz' body hair. 3) Terminal: coarse, pigmented hair found on the scalp, eyebrows, and other regions.

How does the arrector pili muscle affect hair position and skin appearance?

Contraction of the arrector pili muscle (a diagonal band of smooth muscle under autonomic control) pulls the hair follicle perpendicular to the skin surface, causing 'goose bumps' and providing thermal insulation.

What is sebum, and what causes white pimples versus blackheads?

Sebum is an oily, bactericidal secretion from sebaceous glands that prevents skin and hair drying. A white pimple is accumulated sebum in a gland duct, while a blackhead is oxidized and darkened blocked sebum.

What are the characteristics and functions of eccrine sweat glands?

Eccrine glands are the most common merocrine sweat glands that empty directly onto the skin surface. They secrete a watery solution containing NaCl and urea for thermoregulation in response to heat, muscular activity, and stress.

How do apocrine sweat glands differ from eccrine sweat glands?

Apocrine glands are larger, located in regions like the axilla, anus, scrotum, and labia majora, and empty into hair follicles. They secrete a thicker fluid containing lipids and proteins that produces odor when acted upon by bacteria.

What are ceruminous glands and what do they secrete?

Ceruminous glands are modified apocrine sweat glands located in the ear canal that produce cerumen (earwax).

What is the structural difference between epidermal wound healing and deep wound healing?

Epidermal wound healing involves tissue injury restricted strictly to the epidermis, whereas deep wound healing involves injury extending into the dermis and subcutaneous (SubQ) layer.

What are the four phases of deep wound healing in order?

1) Inflammatory phase (vasodilation, increased vascular permeability, white blood cell accumulation), 2) Migratory phase (scab, epithelialization, granulation tissue), 3) Proliferative phase (scar tissue/fibrosis formation), and 4) Maturation phase (resurfaced epithelium).