Untitled Flashcard Set

Integumentary System

Protective covering and first line of defense.

Skin Trivia

21 sq ft, 4 kg/9 lbs, 7–15% of body weight; continuous layer; complex tissues.

One Square Inch of Skin Contains

20 blood vessels, 65 hairs & muscles, 78 nerves, 78 heat sensors, 13 cold sensors, 160 pressure sensors, 100 oil glands, 19,500,000 cells, 0.5 million cells dying/being replaced.

Layers/Regions of the Skin

Epidermis (superficial), Dermis (fibrous connective tissue, vascularized), Hypodermis (fat, anchors skin, absorbs shock).

Functions of Skin

Protection, water balance, temperature regulation, waste disposal, receptor organs, blood reservoir, vitamin D production.

Epidermis

Outer layer of stratified squamous epithelial tissue; avascular; regenerates every 35–45 days; thinner on scalp/armpit than sole.

Layers of Epidermis

Stratum basale, spinosum, granulosum, lucidum, corneum.

Stratum Basale (Germinativum)

Deepest layer; stem cells; melanocytes (10–25%); makes melanin; genetic absence of tyrosinase = albinism.

Stratum Spinosum

Spiny layer; several layers thick; Langerhans cells; tonofilaments resist tension.

Stratum Granulosum

3–5 layers of flattened keratinocytes; keratohyaline granules form keratin; lamellated granules waterproof; slows water loss.

Stratum Lucidum

Clear layer in thick skin (palms, soles); absent in thin skin; 2–3 rows of dead keratinocytes.

Stratum Corneum

Outermost horny layer; 20–30 cell layers; protects deeper cells; dandruff = shedding; hyperkeratosis = thick, dry, scaly skin.

Dermis

Two layers (papillary & reticular); strong, flexible connective tissue.

Characteristics of Dermis

Fibroblasts, macrophages, mast cells, collagen, elastin; wrinkles from loss of elastin/fat.

Papillary Layer of Dermis

Areolar connective tissue; dermal papillae with capillary loops, Meissner’s corpuscles (touch), free nerve endings.

Reticular Layer of Dermis

Dense irregular CT; 80% dermis; collagen & elastin provide stretch/strength.

Contents of Dermis

Blood vessels, capillaries, lymphatics, nerves, hair follicles, sweat glands (eccrine/apocrine), sebaceous glands, ceruminous glands, arrector pili, sensory receptors.

Hair

Pili made of keratin; shaft projects from skin; root embedded; shape = straight/curly; pigment from melanocytes.

Hair Follicle

Root + papilla supplies nutrients; arrector pili raises hair.

Sudoriferous (Sweat) Glands

2.5 million per person; cover most of skin except nipples/genitals.

Eccrine Sweat Glands

Most numerous; palms, soles, forehead; secrete watery sweat (99% water, salts, waste); acidic pH 4–6; temp regulation; no control over emotional sweating.

Apocrine Sweat Glands

Axillary/anogenital; ducts empty into hair follicles; viscous secretion; begins at puberty; sexual scent/stress response.

Ceruminous Glands

Modified apocrine in ear; secrete cerumen (earwax).

Sebaceous (Oil) Glands

All over except palms/soles; secrete oily sebum; lubricates skin/hair; slows water loss; blocked duct = acne.

Nail Structure

Free edge, body, root, lunula, nail folds, nail bed, hyponychium.

Nail Anatomy

Grows under nail matrix; made of keratin; cells replaced if matrix is intact.

Skin Cancer Causes

Benign tumors = warts/moles; malignant = spread; risk: UV, radiation, genetics.

Basal Cell Carcinoma

Most common, least malignant; stratum basale; slow-growing; cured by removal.

Squamous Cell Carcinoma

From keratinocytes in stratum spinosum; scaly red; grows fast, may metastasize; good prognosis if removed early.

Melanoma

Cancer of melanocytes; most dangerous; highly metastatic, resistant to chemo; ABCD rule (Asymmetry, Border, Color, Diameter >6mm).

First-Degree Burns

Only epidermis; redness, pain, swelling; heals in 2–3 days (e.g., sunburn).

Second-Degree Burns

Epidermis + upper dermis; blisters, pain, swelling; heals with some scarring.

Third-Degree Burns

Entire skin destroyed; gray/white/red/black; no pain (nerves destroyed); requires grafts.

Fingerprints

Dermal papillae form ridges; unique to each individual.