Term
| how is the thickness of the skin described? |
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Definition
| it is based on the epidermal thickness |
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Term
order of skin layers:
Stratum _____ |
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Definition
from deep to superfiscial
basale-basile layer, cuboid to columnar, highly mitotically active, attach to hemidesmosomes
spinosum - slighly more irregular, attach to desmosomes; tonofibrils present
granulosum- diamond shaped cells containing kerotohyalin granules. keratin granules attach to many histidine and cystidine rich protein precursors of fillagrin
lucidum- usually only in thick skin, clear thin layer
corneum- outermost, made of keratin and horny scales. dead cells known as squame |
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Term
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Definition
the predominate cell type of epidermis and they produce keratin which is needed to form the water barrier
-created by the deposition of insoluble proteins on the inside of the cell membrane and the outer lipid bilayer |
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Term
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Definition
melanin containing. located at basale layer or below, they can transfer melanin via long entensions through to the cytoplasm of keratinocytes (keratinocytes phagocytose the tips of these projections)
the melanin granules are protective against UV damage
melanocytes come from neural crest cells |
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Term
| formation of the epidermal water barrier |
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Definition
| stratum spinosum is producing keratohyalin granules, but is also producing lamellar bodies which get packaged and exported to fill the intercellular spaces between granulosum and the corneum where they form a lipid envelope |
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Term
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Definition
dendritic cells of mesenchymal origin found mainly in the stratum spinosum
express MHC I and II and uptake Ags from surface and deliver them to lymphnode |
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Term
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Definition
found in stratum basale, these have enhanced sensory preception
bound to neighboring keratinocytes by desmosomes
have neurosecretory granules similar to adrenal medulla |
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Term
| most numberous neuronal receptor in the epidermis? |
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Definition
free nerve endings
surround hair follicles (mechanoreceptors, whiskers)
terminate in stratum granulosum
for fine touch, heat and cold |
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Term
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Definition
deep pressure sensors of mechanical and vibrational pressure. deep to all dermis, goes all the way to periosteum sometimes
myelinated and onion appearance
works by having pressure or vibrations displace the capsule lamellae which depoloarizes the axon |
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Term
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Definition
ÒTouch receptors within dermal papillae
looks like Q-tip
especially responsive to low frequency stimuli on hairless skin |
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Term
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Definition
| located in the dermis, detects mechanical displacement of collagen fibers |
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Term
| what are the layers of the dermis |
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Definition
the papillary layer which is thinner and composed of loose connective tissue
the reticular layer which is composed of dense irregular connective tissue |
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Term
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Definition
-invagination of the epidermis down into dermis, the deepest part of which becomes the germinal matrix (regrowth center)
three segments
infundibulum- seg from surface to opening of sebaceous gland
isthmus- from infundibulum to arrector pilli muscle
inferior segment- growing part |
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Term
| germitive layer of hair growth |
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Definition
3 layers
cuticle: squamous cells
-Huxley’s layer: flattened cells
- Henley’s layer: cuboidal cells in direct contact with outermost part of hair follicle, the external root sheath
Hair emerges follicle completely keratinized
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Term
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Definition
ÒMedulla – central, soft keratin, large vacuolated cells; only present in thick hair
ÒCortex – peripheral to medulla, cells here undergo differentiation into keratin-filled cells;contains pigment
ÒCuticle of hair shaft – outermost layer of hair composed of very thin scale-like cells |
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Term
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Definition
located at the upper third of the hair follicle, they secrete sebum which oils and lubricates the cells
proliferation of cells in the basal layer of the gland. these cells accumulate fatty material in their cytoplasm and eventually burst expelling the material (this is sebum). this progess continues and can be sped up by the contraction of arrector pilli muscles. |
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Term
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Definition
ÒEccrine – most common, distributed all over body except lips and part of the external genitalia. independent from hair cells. below dermis in subQ tissue. major role is temperature reg. sweat is hypotonic, undergo reabsorption
ÒApocrine – limited to axilla, areola, nipple, skin around anus and external genitalia; store secretory protein. release phermones. become fxnl at puberty. connected to hair follicles. do not undergo reabsorption |
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Term
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Definition
ÒClear cells – abundant glycogen, pale cytoplasm, cuboidal to simple columnar; secrete H20, NaCl, urea. Canaliculi conduct sweat to lumen of ducts
ÒDark cells – secretory granules, secrete glycoprotein (proteoglycans)
ÒMyoepithelial cells – basal aspect, oriented obliquely and longitudinally around secretory portions of tubules, spindle shaped; contractions aid in expelling sweat; the excretory duct does NOT have myoepithelial cells |
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Term
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Definition
connects to connective tissue sheath of hair follicle
produces goosebumps and dimpling of skin, causes hair to stand on ends |
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Term
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Definition
lie on top of nail bed. originate in 3rd month of embryological development. stratum granulosum-less
epidermis of fingers and toes invade underlying dermis
made of hard keratin with a high sulfur content |
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Term
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Definition
ÒCrescent-shaped white area near nail root – lunula: color is from thick, opaque layer of partially keratinized matrix cells
ÒEponychium (cuticle) – edge of skin fold covering nail root, also hard keratin, does not desquamate
ÒHyponychium – epidermis underlying distal tip of nail where stratum corneum of distal free edge contacts the nail; thickened epidermal layer which secures the free edge of the nail plate at fingertip |
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