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63 terms

Structure of Skin

STUDY
PLAY
skin
the body's largest organ in terms of surface area and weight
skin
would cover 1.5-2.0 square meters of surface area if flattened
skin
makes up about 15% of total body weight
skin
consists of a superficial epidermis and a deeper dermis; below this the hypodermis, which is a layer of connective tissue
thick skin
has five epidermal layers and covers the palms, soles, fingers, and toes with surface layer of dead cells and it lacks hair follicles
thin skin
has four thinner epidermal layers and covers all other parts of the body
dermatology
the study and treatment of the integument adn the appearance and/or condition of one's kin can provide diagnostic information regarding one's overall health
epidermis
consists of keratinized stratified squamous epithelium that is organized into several distinct strata
epidermis
contains no blood vessels, so its cells depend on diffusion of oxygen adn nutrients from blood vessels in underlying connective tissue
stratum basale
consists of a single layer of cuboidal or columnar cells that continuously undergo mitotic cell division to produce new skin cells
keratinocytes
are teh most abundant cells and are held together by desmosomes
keratinocytes
filled with tough, fibrous keratin that protects skin from heat microbes, chemicals
keratinocytes
help waterproof skin
melanocytes
synthesize the pigment melanin
melanin
is responsisble for skin color and it absorbs ultraviolet radiation to protect from damaging effects of sunlight
merkel cells
are touch receptors that join with sensory neurons to form merkel discs
stratum spinosum
consists of several layers of keratinocytes
stratum spinosum
when skin is prepared for microscope slides, keratinocytes shrink and pull apart, except where attached by desosomes, giving this layer "spiny" appearance
dedritic (langerhans) cells
are macrophages that protect the body
dendritic (langerhans) cells
arise in bone marrow and migrate to epidermis to protect against microbes that invade skin
stratum granulosum
consists of keratinocytes that contain dark-staining granules of protein that eventually become keratin
keratinocytes
die and release waterproofing glycolipids that form a barrier between the stratum spinosum and the stratum granulosum
stratum lucidum
a thin, translucent layer of dead cells found only in thick skin
stratum corneum
contains up to 30 layers of dead, scaly keratinized cells and makes up about 75% of the thickness of the epidermis
dander
it takes 30-40 days for a keratinocyte to migrate to the skin's surface and exfoliate as . . . . .
dander
mots household dist is made up of this when it doesn't get eliminated
dander
presence of this in bedding provides food for dust mites
thickened callus
persisten friction with the stratum corneum can cause this to occur
feces of dust mites
allergy to household dust is actually allergy to . . . . .
dermis
consists of connective tissue comrpised mainly of collagen fibers, but elastic fibers, reticular fibers, fibroblasts, and macrophages are also present
dermal papillae
boundary between dermis and epidermis
finger-like projections
extend into the epidermis to form epidermal ridges on palsm, fingers, soles, toes, that increase grip by increasing friction
secretions
. . . . at these surfaces form fingerprints or footprints on objects
superficial zone
papillary layer
superficial zone
comprised of areolar connective tissue that contains elastic fibers
superficial zone
contains capillaries, touch receptors (Meissner's corpuscles), adn free nerve endings
deeper zone
reticular layer
deeper zone
comprised of dense irregular connective tissue that c ontains collagen bundles
deeper zoen
contains adipocytes, hair follicles, nerves, oil glands, and the ducts of sweat glands
subcutaneous layer
beneath the dermis is the subcutaneous hypodermis or superficial fascia
subcutaneous layer
consits of areolar tissue adn adipose tissue
subcutaneous layer
binds skin to underlying tissue, cushions body, provides thermal insulation, stores energy
subcutaneous layer
numerous blood vessels supply skin with oxygen adn nutrients and provide pathway for rapid absorption of drugs and/or mediciines into bloodstream
subcutaneous layer
contains nerve endings (pacinian corpuscles); sensitive to pressure
skin color
determined by genes that control interactiosn among melanin and carotene and hemoglobin
melanin
produces variations in skin color that range from pale yellow to black
ultraviolet radiation (sunlight)
stimulates melanocytes to increase their production of melanin, so the skin becomes darker
melanin
tends to be plentiful in face, limbs, around nipples, external genitalia
dark skin
melanin breaks down slowly making it visible in all epidermal layers
light skin
melanin breaks down rapidly making it less visible beyond stratum basale
freckles
flat patches of skin where melanin accumulates
moles
elevated patches of skin where melanin accumulates
vitiligo
results from partial or complete loss of melanocytes in patches of skin and produces irregular whtie blotches
carotene
is a yellow-orange pigment that accumulates in the stratum corneum or sub-cutaneous fat,which gives the skin a yellowish tint
translucent
results when melanin and carotene are in short supply, epidermis is . . . . .
hemoglobin
molecules in the blood become visible, producing pinkish flesh tones typical of caucasian skin
erythema
describes abnormal redness due to the dilation of dermal blood vessels during strenuous exercise or heat or anger of embarrasment
cyanosis
describes blueness of the skin due to insufficient oxygen in the blood because of airway obstructions or lung disease or cold weather
jaundice
a yellowing of the skin and whties of the eyes due to elevated levels of bilirubin in the blood, which is unable to be disposed fo by the liver
pallor
describes pale skin due to reduces dermal blood flow because of low blood pressure or shock of anemia or emotional stress
albinism
is a genetic defect that restults in a lack of teh amino acid tyrosine, which blocks the synthesis of melanin and produces pale skin, white hair, and pink eyes
hematoma
is a visible blood clot caused by trauma to the skin, which produces a bruise
hemangiomas
are "birthmarks" caused by benign tumors of dermal blood vessels