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