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Histology > Skin Part 2 > Flashcards

Skin Part 2 Flashcards

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
Q

melanin is useful in distinguishing

A

tumor types, e.g., melanoma vs. squamous cell carcinoma

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26
Q

melanin functions (2)

A

functions as a UV shield to protect the nucleus and inhibit mutagenesis
neural development

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27
Q

DNA subject to damage by

A

UV

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28
Q

Langerhans cells (fixed tissue macrophage)

A

phagocytic, Ag presenting cells

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29
Q

Contain distinctive — —, visible on EM

A

Birbeck granules

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30
Q

where are Langerhans cells located?

A

within stratum spinosum

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31
Q

langerhans cells are involved in

A

contract allergic dematitus

32
Q

do langerhans cells stain well on H&E?

A

no

33
Q

langerhans cells contain abundant

A

cytoplasmic extensions

34
Q

Skin appendages

A

embryological outgrowths of epidermis

35
Q

examples of skin appendages? (5)

A

hair, nails, sebaceous & sweat glands; horns

36
Q

terminal hair

A

coarse hair on scalp, axillae, & pubis

37
Q

Hair shaft consists of (2)

A

outer cortex & inner medulla

38
Q

Shaft covered by thin — of overlapping keratin plates

A

cuticle

39
Q

overlapping keratin plates prevents

A

matting

40
Q

Hair shaft produced by

A

hair follicles

41
Q

cylindrical downgrowths of epithelium surrounded by

A

collagen sheaths

42
Q

Hair growth occurs within in deep terminal expansion of follicle,

A

hair bulb (=hair root)

43
Q

Hair bulb lined by actively dividing epithelial cells homologous to

A

stratum basale

44
Q

At base of bulb is a vascular core,

A

dermal papilla

45
Q

dermal papillary/vascular core

A

finger-like invagination of dermis containing blood vessels

46
Q

As epithelial cells lining hair bulb mature, fill with hard keratin filaments arranged in

A

parallel bundles

47
Q

Melanocytes adjacent to hair follicle produce melanin, becomes incorporated into cortex to result in

A

hair color

48
Q

Developing hair surrounded & protected by – and – root sheath which line hair follicle

A

internal & external

49
Q

Glassy membrane, a modified basement membrane, separates

A

hair bulb from surrounding dermis

50
Q

Hair aids in (2)

A

protection & thermoregulation

51
Q

where is hair absent? (2)

A

thick skin of palms & soles

52
Q

Bundles of smooth Mm cells (arrector pili M) attach to hair follicle sheath & insert on

A

epidermal ridges

53
Q

contraction raises hair, resulting in

A

“goose bumps”

54
Q

piloerection

A

bundles of smooth Mm cells (arrector pili M) attach to hair follicle sheath & insert on epidermal ridges; contraction raises hair => “goose bumps”

55
Q

piloerection is caused by sympathetic stimulation due to (3)

A

cold/ fear/ aggression

56
Q

is hair growth continuous?

A

no

57
Q

Growth phase

A

anagen

58
Q

Involuting phase (loss of blood supply)

A

catagen

59
Q

Inactive resting phase

A

telogen

60
Q

Shedding of old hair shaft

A

exogen

61
Q

Fine body hair in children & women referred to as — hair

A

vellus

62
Q

At puberty, vellus hair replaced by coarser — hairs

A

terminal

63
Q

— — is the most common form of hair loss, affecting 30-40% of adults

A

Androgenic alopecia

64
Q

Androgenic alopecia is (2) dependent

A

genetic and androgen dependent

65
Q

Affected individuals have high levels of —

A

5-α-reductase

66
Q

5-α-reductase

A

the enzyme that converts testosterone to dihydroxytestosterone

67
Q

conversion of testosterone to dihydroxytestosterone results in

A

follicular atrophy

68
Q

— nails unique to primates

A

flattened

69
Q

Nail consists of flattened nail plate—rests on

A

stratified squamous epithelium of nail bed

70
Q

hyponichium

A

stratified squamous epithelium of nail bed

71
Q

Proximal end of nail, nail root, extends into dermis, attaches to

A

periosteum of distal phalanx

72
Q

Nail growth occurs by proliferation & differentiation of epithelium at nail root in

A

germinative zone of nail matrix

73
Q

nail matrix

A

underlies white crescent at base of nail, lunula, covered by superficial cuticle, or eponychium

74
Q

as epithelial cells mature, fill with keratin & die, they form the

A

nail plate

75
Q

nail plate consists of

A

densely packed, parallel, hard keratinfilaments embedded in amorphous matrix

76
Q

nail plate slides over underlying nail bed epithelium as

A

it grows

Histology (32 decks)

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