Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
53 Cards in this Set
- Front
- Back
|
what are the layers of the skin
|
epidermis
epidermo-dermal jcn dermis (papillary, reticular, hypodermis) |
|
|
features of epidermo-dermal jcn?
|
series of interlocking ridges and valleys that increase surface contact for nourishment, sensation, and tight binding
|
|
|
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 |
|
|
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 |
|
|
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 |
|
|
hypodermis-- type of tissue, blood supply
|
adipose tissue or fascia bound to bone
may contain large supplying blood vv |
|
|
what are the 5 layers of the epidermis
|
stratum basale
stratum spinosum stratum granulosum stratum lucidum stratum corneum |
|
|
stratum basale-- type of epithelium
|
single layer of cuboidal or columnar "committed stem cells" w/high mitotic index (and highest at night)
|
|
|
stratum basale cells are bound to what? via what?
|
bound to a thick basal lamina via hemidesmosomes, and bound to each other via desmosomes
|
|
|
what organelles to stratum basale cells contain?
|
SER, free polysomes, bundles of keratin filaments
|
|
|
stratum spinosum--cell shapes? connected via?
|
many layers of cuboidal to flattened oval cells joined by many desmosomes, linked to masses of cytoplasmic keratin
|
|
|
what else does cytoplasm of spinosum cells contain?
|
SER, free polysomes, vesicles containing membrane coating granules (rich in glyocolipid acylglucosylcerimide)
|
|
|
stratum granulosum-- main purpose of this layer?
basic structure? |
for strength and water resistance
3-5 layers of oval to flattened cells |
|
|
what makes granulosum water resistant?
|
membrane coating granules are pushed toward the cell membrane and excreted to form multiple layers of lipid-rich, water-repellent material between the cells
|
|
|
what other granules are in the cytoplasm of granulosum?
|
keratohyalin granules- contain keratohylain and filaggrin
these granules are not membrane bound- are in close contact w/and penetrated by masses of keratin filaments |
|
|
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 |
|
|
lucidum cytoplasm contains?
|
keratohyalin granules and keratin bundles
|
|
|
stratum corneum-- cell characteristics
|
layers of organelle-less, lifeless squames, very flat & thin-- one cell may span area as much as 15 basal cells
|
|
|
squames are essentially what?
|
flattened masses of keratin
may be loosely bound in thin layers (scalp, back of hand) or tightly bound in thick layer (palms or soles) |
|
|
keratinization is stimulated by ____
is supressed by ____ |
stimulated by EGF (epidermal growth factor)
supressed by TGF (transforming growth factor) |
|
|
some of TGF and EGF are made by what?
|
the keratinocytes themselves-- so they're self-regulating to some extent
|
|
|
how long does it take cells of stratum basale to complete a life cycle?
|
20-30 days-- then they're shed
mitosis occurs primarily at night |
|
|
is there one type of keratin?
|
no-- many types
|
|
|
langerhans cell-- what's its shape, where is it located
|
a stellate cell, extends processes between cells in the outer stratum spinosum of skin, oral mucosa, vagina, and esophagus
|
|
|
where are langerhans cells derived from?
|
bone marrow
|
|
|
langerhans represent what % of skin cells?
|
3-8%
|
|
|
what do langerhans cells contain?
|
cytoplasmic vermiform (birbeck) granules-- unknown fcn
|
|
|
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 |
|
|
merkel cell shape and location
innervation? |
stellate cells, found in stratum basale
innervated basale |
|
|
what does merkel cell cytoplasm contain
|
dense core granules similar to those in neuroendocrine cells (granule content not known)
|
|
|
where are merkel cells most abundant?
|
in sensory areas like fingertips, believed to be mechanoreceptors
|
|
|
melanocyte location? shape?
|
stratum basale or in adjacent dermis
stellate |
|
|
what do melanocytes synthesize?
|
melanosomes containing melanin pigment
|
|
|
how is melanin produced?
|
from tyrosine, by action of tyrosinase, w/in melanosomes
|
|
|
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) |
|
|
what two things determine skin color?
|
tyrosinase activity (determines amt and size of melanin granules)
and rate of degradation of melanin granules |
|
|
what two things determine skin color?
|
tyrosinase activity (determines amt and size of melanin granules)
and rate of degradation of melanin granules NOT melanocyte number |
|
|
what causes difference between light and dark races?
|
more lysosomal activity in the keratinocytes in light races, so melanin more rapidly degraded
in dark races melanin may persist to stratum corneum |
|
|
how do melanosomes get to keratinocytes?
|
melanosomes are released extracellularly and are phagocytosed by keratinocytes, which place them above their own nuclei
|
|
|
invagination of epidermis yields what?
|
hair follicles (and their sebaceous glands), sweat glands, and nail beds
|
|
|
what layer of skin is source of all skin accessories/appendages?
|
stratum basale-- by specialized differentiation and/or specialized keratinization processes
|
|
|
hair bulb formation
hair bulb nourished by what |
invagination of an epidermal peg deep into dermis
nourished by vascular dermal papilla |
|
|
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 |
|
|
what holds keratin fibers of hair together?
|
"glue protein" tricholyaline (similar to filaggrin of keratohyaline granules)
holds fibers together to form the hard keratin forming the hair shaft |
|
|
layers of sheath of follicle
|
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 |
|
|
how does hair achieve color?
|
color is added by melanocytes in the hair matrix layer
|
|
|
arrector pili muscle
|
sm muscle that connects hair follicle to the papillary dermis
contraction tilts hair to more erect position |
|
|
following a skin abrasion, where is the best place for regeneration to come from?
|
the region of basale in the hair follicle near the sebaceous gland called the "bulge region"
|
|
|
how are nails formed? what does nail matrix consist of?
|
invagination of the epidermis forms nail matrix
consists of stratum basale and spinosum |
|
|
eponychium and hyponychium
|
where the stratum corneum overlaps the nail at the proximal (epo) and distal (hypo) ends
|
|
|
cells in upper portion of stratum spinosum of nail matrix?
|
fill w/masses of sulfur-rich, keratin filaments which arebound together by a "keratohyalin-like" substance into a hard plate
|
|
|
nail bed is made of what two layers?
|
stratum basale and spinosum
|
|
|
nail bed lies on what?
|
very linear dermal ridges
|
