histoPP4.txt

barrier system (water, microorganisms, UV light), thermoregulation, plasticity, elasticity

dermis, epidermis, hypodermis (subcutaneous tissue)

thick skin (hands, soles of feet), thin skin (everywhere else)

stratum basale, spinosum, granulosum, lucidum, corneum

single layer of cuboidal cells forming the basal layer sitting on the basement membrane. function - intense mitotic division for use in skin

filled with keratin and desmosomes to bind cells tightly together (f - resists abrasion)

3-5 layers squamous cells that secrete lipid rich cellular "cement" (cements/seals skin)

more in thick skin, translucent layer packed with keratin and no organelles (resists abrasion)

the "dead layer," a layer of organelleless keratinized cells that slough off constantly (desquamation)

keratinocytes (cell in any/all layers), melanocytes (UV protection), langerhans (immunity)

synthesize melanin in deeper layers of skin

melanocyte number constant, melanin granule count not constant. When tanning, melanocytes create more melanin granules and existing granules become darker

macrophages of the skin regions. Found in basale and spinosum, bone marrow derived, can bind/present antigens for immunity building

aka hypodermis and superficial fascia, fat cells, neurovascular networks, loose CT binding underlying structures

holocrine (entire contents of cell), merocrine (exocytosis), apocrine (a portion of cytosol released)

epithelial cells with sebum (lipids) conc. in face/scalp. secrete sebum onto hair follicles for anti fungal, bacteria

they release the sebum along with dead cells, basal layer of gland regenerates cells

coiled glands that release sweat onto skin surface (thermoregulation)

release viscous odorless fluid that smells when bacteria digest it. Released in armpits, anus, genitals

nail bed is spinosum and basale only, modified epithelium, cuticle is stratum corneum

epidermis invagination, dermal papilla contains cells for growth and blood supply, arrector pillae = goosebumps, melanocytes provide pigment

catagen (2-3 week phase of no growth), anagen (growth phase 30days to 6 years), telogen (resting phase, no growth, possible hair loss)

decreased elasticity, atrophy of strata, reduced sweating

• during activity - less, shunted to muscles except altered in hot environments
• during rest - is allowed more

hyperplasia (callous) increased sweat ability, blisters (fluid deposition between dermis, epidermis by excessive shearing)

skin breakdown (decubitus ulcer) at bony prominences (heels, sacrum, greater trochanter, scapula, elbows, back of head)