Skin

Skin

Insulates, cushions the underlying body tissue, protects the entire body from mechanical damage, chemical damage, thermal damage, bacterial damage

Cornfield layer

Hardened uppermost layer; prevents water loss

Capillary network

Regulating heat loss from the body surface

Dermis

Underlying connective tissue

Avascular epidermis

Keratinized stratified squamous epithelium

Keratinocytes

Most abundant epidermal cells;produce keratin fibrils; connected to each other by desmosomes

Keratin

Fibrous protein that gives the epidermis durability and protective capabilities

Melanocytes

Spidery black cells that produce melanin

Melanin

Nuclei of the cells in the deeper epidermal layers; shielding their genetic material from damaging effects of ultraviolet radiation

Epidermal dendritic cells

Langerhans cells; immunity

Tactile (merkel) cells

Conjunction with sensory nerve endings; sensitive touch receptors

Stratum Basale

Constantly undergoing mitotic cell division> stratum germinativum; 10% to 25% are melanocytes; receive adequate nourishment via diffusion of nutrients from the dermis

Stratum spinosum

thick weblike bundles of intermediate filaments made of a pre-keratin protein; receive adequate nourishment via diffusion of nutrients from the dermis

Stratum granulosum

abundant granules contained by cells 2 types; lamellated> waterproofing glycolipid secreted into extracellular space, Keratohyaline> forms the keratin fibrils

Stratum lucidum

translucent bond of flattened dead keratinocytes

stratum corneum

20 to 30 layers; cells are dead and flattened scalelike remnants are fully keratinized

papillary layer

composed of areolar connective tissue; uneven; superior surface> dermal papillae- attach it to epidermis above; allows heat to radiate to the skin surface, pain, touch receptors

reticular layer

deepest skin layer, dense irregular C.T.; contains arteries, veins, seat, sebaceous glands, pressure receptors

Papillary & Reticular

collagenic and elastic fibers; fibroblasts, adipose cells, various types of macrophages& various others found in dermis

Bedsores

restriction of the blood supply and tissue death

skin color

amount of melanin, relative amount of carotene in skin, and oxygenation of the blood

Hair

consists of medulla, surrounded 1st by cortex then protective cuticle

root

portion of hair enclosed in the follicle

shaft

projects from the surface of the scalp; bulk is dead material

hair bulb

germinal epithelial cells at the basal end of the follicle

follicle

formed by epidermal and dermal cells; enclosed by thickened basement & glassy membrane, C.T. root sheath

papilla

protrudes into the hair bulb from the C.T. sheath & provides nutrition to growing hair

Arrector pili muscle

smooth muscle cells connect each hair follicle to the papillary layer; muscles contract> hair follicle is pulled upright ( goose bump)

Sebaceous glands

empty into a hair follicle, some open on the skin surface; are not on palms of hands or soles of feet

Sebum

product of sebaceous glands, oily substances & fragmented cells that acts as a lubricant to keep the skin soft and moist

black heads

dried sebum, bacteria, and melanin in oil duct

Acne

active infection or sebaceous glands

eccrine glands

produce clear perspiration consisting promarily of water, salts, & urea; secrete perspiration when temp. or body temp. is high

Apocrine glands

axillary & genital areas; milky protein and fat rich substance; excellent nutrient for microorganisms in skin

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