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53 Cards in this Set
- Front
- Back
what are the layers of the skin
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epidermis
epidermo-dermal jcn dermis (papillary, reticular, hypodermis) |
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features of epidermo-dermal jcn?
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series of interlocking ridges and valleys that increase surface contact for nourishment, sensation, and tight binding
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type of tissue of papillary dermis?
location? blood supply? |
dense CT, just deep to epidermis
rich capillary bed arranged mostly parallel to and close to the overlying epidermis also a second layer of mostly horizontal, larger blood vv is present deeper in papillary dermis |
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types of cells in papillary dermis?
types of collagen/fibers? |
contains fibroblasts, and is infiltrated by mast cells, lymphocytes, melanocytes, macs, and plasma cells
contains collagen III and I, and fine elastic fibers |
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reticular dermis-- type of tissue, types of fibers
predominant cell type? |
dense irregular CT, containing mostly collagen I and a few thick elastic fibers
fibroblast is predominant cell type |
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hypodermis-- type of tissue, blood supply
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adipose tissue or fascia bound to bone
may contain large supplying blood vv |
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what are the 5 layers of the epidermis
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stratum basale
stratum spinosum stratum granulosum stratum lucidum stratum corneum |
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stratum basale-- type of epithelium
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single layer of cuboidal or columnar "committed stem cells" w/high mitotic index (and highest at night)
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stratum basale cells are bound to what? via what?
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bound to a thick basal lamina via hemidesmosomes, and bound to each other via desmosomes
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what organelles to stratum basale cells contain?
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SER, free polysomes, bundles of keratin filaments
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stratum spinosum--cell shapes? connected via?
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many layers of cuboidal to flattened oval cells joined by many desmosomes, linked to masses of cytoplasmic keratin
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what else does cytoplasm of spinosum cells contain?
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SER, free polysomes, vesicles containing membrane coating granules (rich in glyocolipid acylglucosylcerimide)
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stratum granulosum-- main purpose of this layer?
basic structure? |
for strength and water resistance
3-5 layers of oval to flattened cells |
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what makes granulosum water resistant?
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membrane coating granules are pushed toward the cell membrane and excreted to form multiple layers of lipid-rich, water-repellent material between the cells
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what other granules are in the cytoplasm of granulosum?
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keratohyalin granules- contain keratohylain and filaggrin
these granules are not membrane bound- are in close contact w/and penetrated by masses of keratin filaments |
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stratum lucidum-- locations on body?
types of cells? |
usu only seen on skin of palms and soles
several layers of very flat, refractile cells w/deteriorating organelles and nuclei |
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lucidum cytoplasm contains?
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keratohyalin granules and keratin bundles
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stratum corneum-- cell characteristics
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layers of organelle-less, lifeless squames, very flat & thin-- one cell may span area as much as 15 basal cells
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squames are essentially what?
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flattened masses of keratin
may be loosely bound in thin layers (scalp, back of hand) or tightly bound in thick layer (palms or soles) |
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keratinization is stimulated by ____
is supressed by ____ |
stimulated by EGF (epidermal growth factor)
supressed by TGF (transforming growth factor) |
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some of TGF and EGF are made by what?
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the keratinocytes themselves-- so they're self-regulating to some extent
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how long does it take cells of stratum basale to complete a life cycle?
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20-30 days-- then they're shed
mitosis occurs primarily at night |
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is there one type of keratin?
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no-- many types
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langerhans cell-- what's its shape, where is it located
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a stellate cell, extends processes between cells in the outer stratum spinosum of skin, oral mucosa, vagina, and esophagus
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where are langerhans cells derived from?
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bone marrow
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langerhans represent what % of skin cells?
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3-8%
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what do langerhans cells contain?
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cytoplasmic vermiform (birbeck) granules-- unknown fcn
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what do langerhans cells do?
they have been linked to what? |
they bind to IgG, IgA, complement 3, phagocytize foreign antigens, migrate to regional nodes, and present antigen to regional lymphocytes
have been linked to contact dermatitis inflammation rxns |
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merkel cell shape and location
innervation? |
stellate cells, found in stratum basale
innervated basale |
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what does merkel cell cytoplasm contain
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dense core granules similar to those in neuroendocrine cells (granule content not known)
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where are merkel cells most abundant?
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in sensory areas like fingertips, believed to be mechanoreceptors
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melanocyte location? shape?
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stratum basale or in adjacent dermis
stellate |
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what do melanocytes synthesize?
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melanosomes containing melanin pigment
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how is melanin produced?
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from tyrosine, by action of tyrosinase, w/in melanosomes
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how does tyrosinase work?
what is tyrosinase activity stimulated by? |
oxidizes tyrosine to 3,4 dihydrophenalananin (DOPA) and dopaquinone
stimulated by uv light and MSH (melanocyte stimulating hormone) |
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what two things determine skin color?
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tyrosinase activity (determines amt and size of melanin granules)
and rate of degradation of melanin granules |
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what two things determine skin color?
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tyrosinase activity (determines amt and size of melanin granules)
and rate of degradation of melanin granules NOT melanocyte number |
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what causes difference between light and dark races?
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more lysosomal activity in the keratinocytes in light races, so melanin more rapidly degraded
in dark races melanin may persist to stratum corneum |
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how do melanosomes get to keratinocytes?
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melanosomes are released extracellularly and are phagocytosed by keratinocytes, which place them above their own nuclei
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invagination of epidermis yields what?
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hair follicles (and their sebaceous glands), sweat glands, and nail beds
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what layer of skin is source of all skin accessories/appendages?
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stratum basale-- by specialized differentiation and/or specialized keratinization processes
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hair bulb formation
hair bulb nourished by what |
invagination of an epidermal peg deep into dermis
nourished by vascular dermal papilla |
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what does the hair matrix consist of?
what portion of matrix synthesizes each portion of hair shaft? |
consists of modified stratum basale
medulla synthesizes vacuolated cells cortex-- keratinized cells cuticle-- heavily keratinized cells |
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what holds keratin fibers of hair together?
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"glue protein" tricholyaline (similar to filaggrin of keratohyaline granules)
holds fibers together to form the hard keratin forming the hair shaft |
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layers of sheath of follicle
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mimic normal layers of the epidermis
inner root sheath is where stratum corneum would be outer root sheathis where granulosum, spinosum, and basale would be |
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how does hair achieve color?
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color is added by melanocytes in the hair matrix layer
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arrector pili muscle
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sm muscle that connects hair follicle to the papillary dermis
contraction tilts hair to more erect position |
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following a skin abrasion, where is the best place for regeneration to come from?
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the region of basale in the hair follicle near the sebaceous gland called the "bulge region"
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how are nails formed? what does nail matrix consist of?
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invagination of the epidermis forms nail matrix
consists of stratum basale and spinosum |
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eponychium and hyponychium
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where the stratum corneum overlaps the nail at the proximal (epo) and distal (hypo) ends
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cells in upper portion of stratum spinosum of nail matrix?
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fill w/masses of sulfur-rich, keratin filaments which arebound together by a "keratohyalin-like" substance into a hard plate
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nail bed is made of what two layers?
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stratum basale and spinosum
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nail bed lies on what?
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very linear dermal ridges
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