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Skin Part 2 Flashcards

(76 cards)

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1
Q

neuroectrodermal dendritic cells are present in the

A

epidermis

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2
Q

neuroectodermal cells are of what origin

A

neural crest origin

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3
Q

melanocytes have a small number of cells, usually restricted to the

A

basal layer

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4
Q

extensive cytoplasmic processes may extend into the

A

stratum spinosum

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5
Q

melanocytes are responsible for the production of

A

melanin

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6
Q

melanin

A

skin pigment

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7
Q

melanin released from melanocytes in organelles called

A

melanosomes

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8
Q

melanin is taken up by

A

surrounding epidermal cells

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9
Q

two types of melanocytes

A

eumelanin

phenomelanin

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10
Q

eumelanin

A

dark brown pigment

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11
Q

eumelanin is present in

A

dark haired individuals

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12
Q

pheomelanin

A

red to yellow pigment

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13
Q

pheomelanin is present in

A

individuals with red or blonde hair

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14
Q

equal numbers of melanocytes in all individuals, but variable rates of melanin production and degradation by

A

lysosomal enzymes

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15
Q

pigment in lighter skinned individuals vs darker skinned individuals

A

lighter skinned individuals produce less pigment or digest pigment faster. darker skinned individuals produce and retain more pigment longer

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16
Q

vitiligo

A

autoimmune disease which results in destruction of melanocytes which results in depigmentation

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17
Q

melanin synthesis is under the control of the pituitary hormone

A

melanocytes stimulating hormone (MSH)

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18
Q

To produce melanin, tyrosineprecursor first oxidized to

A

DOPA

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19
Q

To produce melanin, tyrosine precursor first oxidized to DOPA (3,4-dihydroxyphenalalanine) by

A

tyrosinase

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20
Q

where is tyrosinase located?

A

in organelles called premelanosomes

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21
Q

Followed by conversion of DOPA to

A

melanin in melanosomes

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22
Q

Albinos lack tyrosinase, so — & melanin not formed

A

DOPA

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23
Q

Premelanosomes form, but

A

do not mature

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24
Q

Tyrosinase can be used as a marker, to differentiate

A

melanocytes from keratinocytes containing phagocytosed melanin

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25
melanin is useful in distinguishing
tumor types, e.g., melanoma vs. squamous cell carcinoma
26
melanin functions (2)
functions as a UV shield to protect the nucleus and inhibit mutagenesis neural development
27
DNA subject to damage by
UV
28
Langerhans cells (fixed tissue macrophage)
phagocytic, Ag presenting cells
29
Contain distinctive --- ---, visible on EM
Birbeck granules
30
where are Langerhans cells located?
within stratum spinosum
31
langerhans cells are involved in
contract allergic dematitus
32
do langerhans cells stain well on H&E?
no
33
langerhans cells contain abundant
cytoplasmic extensions
34
Skin appendages
embryological outgrowths of epidermis
35
examples of skin appendages? (5)
hair, nails, sebaceous & sweat glands; horns
36
terminal hair
coarse hair on scalp, axillae, & pubis
37
Hair shaft consists of (2)
outer cortex & inner medulla
38
Shaft covered by thin --- of overlapping keratin plates
cuticle
39
overlapping keratin plates prevents
matting
40
Hair shaft produced by
hair follicles
41
cylindrical downgrowths of epithelium surrounded by
collagen sheaths
42
Hair growth occurs within in deep terminal expansion of follicle,
hair bulb (=hair root)
43
Hair bulb lined by actively dividing epithelial cells homologous to
stratum basale
44
At base of bulb is a vascular core,
dermal papilla
45
dermal papillary/vascular core
finger-like invagination of dermis containing blood vessels
46
As epithelial cells lining hair bulb mature, fill with hard keratin filaments arranged in
parallel bundles
47
Melanocytes adjacent to hair follicle produce melanin, becomes incorporated into cortex to result in
hair color
48
Developing hair surrounded & protected by -- and -- root sheath which line hair follicle
internal & external
49
Glassy membrane, a modified basement membrane, separates
hair bulb from surrounding dermis
50
Hair aids in (2)
protection & thermoregulation
51
where is hair absent? (2)
thick skin of palms & soles
52
Bundles of smooth Mm cells (arrector pili M) attach to hair follicle sheath & insert on
epidermal ridges
53
contraction raises hair, resulting in
“goose bumps”
54
piloerection
bundles of smooth Mm cells (arrector pili M) attach to hair follicle sheath & insert on epidermal ridges; contraction raises hair => “goose bumps”
55
piloerection is caused by sympathetic stimulation due to (3)
cold/ fear/ aggression
56
is hair growth continuous?
no
57
Growth phase
anagen
58
Involuting phase (loss of blood supply)
catagen
59
Inactive resting phase
telogen
60
Shedding of old hair shaft
exogen
61
Fine body hair in children & women referred to as --- hair
vellus
62
At puberty, vellus hair replaced by coarser --- hairs
terminal
63
--- --- is the most common form of hair loss, affecting 30-40% of adults
Androgenic alopecia
64
Androgenic alopecia is (2) dependent
genetic and androgen dependent
65
Affected individuals have high levels of ---
5-α-reductase
66
5-α-reductase
the enzyme that converts testosterone to dihydroxytestosterone
67
conversion of testosterone to dihydroxytestosterone results in
follicular atrophy
68
--- nails unique to primates
flattened
69
Nail consists of flattened nail plate—rests on
stratified squamous epithelium of nail bed
70
hyponichium
stratified squamous epithelium of nail bed
71
Proximal end of nail, nail root, extends into dermis, attaches to
periosteum of distal phalanx
72
Nail growth occurs by proliferation & differentiation of epithelium at nail root in
germinative zone of nail matrix
73
nail matrix
underlies white crescent at base of nail, lunula, covered by superficial cuticle, or eponychium
74
as epithelial cells mature, fill with keratin & die, they form the
nail plate
75
nail plate consists of
densely packed, parallel, hard keratinfilaments embedded in amorphous matrix
76
nail plate slides over underlying nail bed epithelium as
it grows

Histology (32 decks)

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