Integumentary System 

cutaneous membrane: outer epidermis, inner dermis

Accessory structures: originate in the dermis, extend through the epidermis to skin surface (hair follicles, exocrine glands, nails)

Subcutaneous layer (hypodermis): below the dermis

Epidermis: stratified squamous epithelium, avascular, nutrients and oxygen diffuse from capillaries in the dermis

CELLS OF EPIDERMIS: Keratinocytes, melanocytes, dendritic, tactile

Keratinocytes: majority of cells, makes keratin, desmosomes

Melanocytes: deep within epidermis, makes melanin, protection from UV damage

Dendritic cells: macrophages (WBC) immunity

Tactile cells: sensory touch receptors

Layers of keratinocytes from deepest to superficial: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

Stratum Basale: single row, actively mitotic, attached to basement membrane, forms a strong bond between the epidermis and dermis; has tactile cells (responds to touch) FORMS NEW KERATINOCYTES VIA MITOSIS

Stratum spinosum: the “spiny layer”; eight to ten layers of keratinocytes bound by desmosomes; cells appear spiny in histological sections; produced by division of cells in stratum basale, some of which continue dividing; contains dendritic cells which are active in immune responses

Stratum granulosum: three to five layers of keratinocytes; most cells stop dividing and produce keratin; forms dense granules, promotes cellular dehydration and cross-linking of keratin fibers; HELPS FORM KERATIN IN SUPERFICIAL LAYERS

Stratum lucidum: found only in thick skin; made of flat, dead keratinocytes

Stratum Corneum: exposed surface of skin; 15 to 30 layers of keratinized cells; PROTECTS SKIN FROM ABRASION; exposed cells are shed after 2 weeks

Dermis Layers: outer papillary layer and deeper reticular layer (80%)

Papillary layer: areolar tissue; contains capillaries, lymphatic vessels, and sensory neurons; PROVIDES NUTRIENTS TO SUPERFICIAL LAYERS

Reticular Layer: dense irregular tissue; contains collagen fibers and elastic fibers; GIVES THE SKIN TOUGHNESS AND ELASTICITY

Subcutaneous layer (hypodermis): adipose tissue; deep to the dermis; connected to reticular layer by connective tissue; stabilizes position of the skin; large arteries and veins; fat

Immediate concerns for tissue damage: Dehydration (fluid loss), eloctrolyte imbalance, infenction

How do you evaluate the severity of burns: rule of nines (% of body burned due to estimate fluid loss)

Basal cell carcinoma: most common; stratum basale cells invade dermis and hypodermis; appears as shiny dome shaped nodules

Squamous cell carcinoma: stratum spinosum keratinocytes, appears as scaly red papules on scalp, ear, lips, hands; fast growing

Melanoma: least common; melanocytes, spreading brown/black patches; quickly metastasizes to lymph and blood

Hair structure: medulla (central core), cortex (intermediate layer), cuticle (surface layer)

Types of hair: vellus hairs (soft fine hairs that cover most of the body’s surface) Terminal hairs (heavy, pigmented hairs on head, eyebrows, and eyelashes)

Sabaceous glands: oil glands, discharge lipid secretion into hair follicles (lubricates and protects hair shaft); inhibits growth of bacteria

Approcrine sweat glands: found in armpits, around nipples, and pubic region; produce stinky, cloudy secretions

Eccrine sweat glands: glands that discharge directly onto the skin; widely distributed; secretions are 99 percent water plus salt

Ceruminous glands: produce earwax

Nails: made of dead cells packed with keratin

Repairing the integument: bleeding, swelling, pain; mast cells trigger inflammatory response, a scab stabilizes and protects the area; macrophages clean the area; fibroblasts and endothelial cells divide producing granulation tissue