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Skin Flashcards

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1
Q

Cell types of the 2 skin layers?

A
  1. epidermis = epithelial layer of ectoderm origin

2. dermis = mesodermal connective tissue

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2
Q

What components strengthen adhesion b/w dermis/epidermis?

A
  • dermal papillae projections

- interdigitate w/ invaginating epidermal ridges

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3
Q

What is consistency of hypodermis?

A

Loose connective tissue w/ pads of adipocytes

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4
Q

Major cell types in epidermis? (4)

A
  1. keratinocytes (epithelium)
  2. melanocytes
  3. Langerhans cells (present antigens)
  4. Merkel cells (tactile epithelial)
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5
Q

4 layers of epidermis?

A
  1. basal layer (stratum basale)
  2. spinous layer (stratum spinosum)
  3. granular layer (stratum granulosum)
  4. stratum corneum
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6
Q

Describe basal layer

A
  • single layer of basophilic cuboidal/columnar cells
  • intense mitotic activity
  • contains progenitor cells (like stem cells) for all other layers
  • keratin production
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7
Q

Describe spinous layer

A
  • thickest layer
  • stratum germinativum is layer where some division still happening
  • tonofibrils are visible bundles near desmosomes
  • thicker in rough skin
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8
Q

Describe cells in spinous layer

A
  • polyhedral
  • central nuclei
  • nucleoli and cytoplasm actively synth keratins
  • short cytoplasmic projections
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9
Q

Describe granular layer

A
  • 3 to 5 layers of flattened cells
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10
Q

Describe cells in granular layer

A
  • cells keratinizing
  • cytoplasm filled w/ basophilic masses called keratohyaline granules
  • lamellar granules exocytosed from keratinocytes to produce lipid-rich layer around cells
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11
Q

What are keratohyaline granules?

A
  • dense, non-membrane-bound masses of filaggrin and proteins assoc w/ keratins of tonofibrils
  • lamellar granules w/ many lamellae and lipids
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12
Q

Describe stratum lucidum

A
  • found only in thick skin
  • thin, translucent layer of flattened eosinophilic keratinocytes
  • held together by desmosomes
  • no nuclei or organelles
  • cytoplasm only has packed keratin filaments
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13
Q

Describe stratum corneum

A
  • 15 to 20 layers of squamous, keratinized cells

- filled w/ birefringent filamentous keratins

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14
Q

What are squames?

A
  • fully keratinized or cornified cells
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15
Q

Cause of psoriasis

A
  • overactive T lymphocytes that trigger autoimmune rxn in skin
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16
Q

Mechanism of psoriasis

A
  • keratocytes produced & differentiate @ accelerated rates
  • thickening of epidermal layers
  • increased keratinization & desquamation
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17
Q

Symptoms of psoriasis

A
  • inflammation
  • redness
  • irritation
  • itching
  • scaling
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18
Q

What are eumelanins?

A
  • brown/black pigments produced by melanocytes
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19
Q

What pigment is found in red hair?

A
  • pheomelanin
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20
Q

LM features of melanocytes?

A
  • pale-staining, rounded cell bodies
  • attached by hemidesmosomes to basal lamina
  • long irregular cytoplasmic extensions that penetrate epidermis
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21
Q

EM features of melanocytes?

A
  • numerous small mitochondria
  • short cisternae of RER
  • well-dvp’d Golgi
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22
Q

Steps in melanin synth

A
  • tyrosinase converts Tyr into DOPA
  • DOPA transformed into melanin
  • melanin matures into melanosomes in vesicles
  • melanosomes transferred to nuclei of keatinocytes
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23
Q

Features & function of Langerhans cells

A
  • most clearly seen in spinous layer
  • present antigens to T lymphocytes
  • cytoplasmic processes extending from cells
  • dendritic
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24
Q

Features & function of Merkel cells

A
  • mechanoreceptors
  • light touch sensation
  • have neurosecretory granules w/ peptides
  • border basal lamina
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25
Cause of bullous pemphigoid?
- abnormalities of dermal-epidermal junction
26
Cause of bullous pemphigus?
- autoimmune damage to intercell junctions b/w keratinocytes
27
Components of papillary layer of dermis
- dermal papillae - loose connective tissue - types 1/3 collagen - anchoring fibrils of type 7 collagen into basal lamina
28
Components of reticular layer of dermis
- thicker than papillary layer - dense irregular connective tissue - bundles of type 1 collagen - more fibers than papillary layer - dermatan sulfate - elastic fibers
29
Where does subpapillary plexus of capillary branches occur?
- b/w papillary & reticular dermal layers
30
Where does deep plexus of blood/lymph vessels occur?
- interface of dermis & subcutaneous layer
31
Describe Meissner corpuscles
- ellipitical structures - consists of sensory axons winding among flattened Schwann cells perpendicular to epidermis in dermal papillae - initiate impulses when light touch against skin deforms their shape
32
Describe lamellated (pacinian) corpuscles
- large oval structures - found deep in reticular dermis & hypodermis - concentric lamellae of flattened Schwann cells/collagen surr highly branched, unmyelinated axon - respond to course touch, pressure, vibrations
33
Describe Krause end bulbs
- simple encapsulated, ovoid structures - extremely thin, collagenous capsules penetrated by a sensory fiber - sense low-freq vibrations in penis and clitoris
34
Describe Ruffini corpuscles
- collagenous, fusiform capsules anchored to connective tissue - sensory axons - stim by stretch or twisting of skin
35
What sep's hair follicle from dermis?
Glassy membrane (acellular hyaline layer)
36
Internal vs. external root sheath
- internal surr initial part of hair root but degenerates above level of sebaceous glands - external covers internal, extends to epidermis
37
What muscles pulls hair shafts to erect position?
Arrector pili smooth mm
38
3 major phases of hair growth cycle?
1. Anagen = long pd of mitotic activity/growth 2. Catagen = brief pd of arrested growth/regression of hair bulb 3. Telogen = final long pd of inactivity
39
What layer of epidermis is the cuticle an extension of?
Stratum corneum
40
What layers of epidermis are included in the nail bed? (2)
1. basal | 2. spinous
41
What category of gland is the sebaceous gland?
Acinar gland
42
What is a pilosebaceous unit comprised of?
- hair follicle | - sebaceous glands
43
What are sebocytes?
- flattened epithelial cells that produce lipids - filled w/ small fat droplets - assoc w/ acini of sebaceous glands - disintegrate near duct to release lipids (sebum)
44
2 types of sweat glands?
1. eccrine sweat glands | 2. apocrine sweat glands
45
3 cell types of secretory part of eccrine sweat glands?
1. pale-staining clear cells on BL that produce sweat 2. dark cells filled w/ eosinophilic granules that line lumen, merocrine secretions 3. myoepithelial cells on BL, contract to move watery secretion into duct
46
When/where are apocrine glands found?
- after puberty | - skin of axillary & perineal regions
47
Histo diff's b/w apocrine and eccrine sweat glands?
- eccrine: stratified cuboidal, pale-staining | - apocrine: larger lumens, simple cuboidal, eosinophilic, many secretory granules
48
What type of secretion do apocrine glands do?
Merocrine (exocytosis of granules)
49
Diff's in innervations of apocrine/eccrine glands?
- apocrine = adrenergic nerve endings | - eccrine = cholinergic nerve endings
50
What are embryologic precursors to melanocytes?
Neural crest cells
51
What are points of adhesion in melanocytes?
- hemidesmosomes to BL | - no desmosomes
52
Helpful feature to ID hypodermis?
- presence of adipocytes
53
What 3 sensations do Pacinian corpuscles register?
1. coarse touch 2. pressure from sustained touch 3. vibration
54
Defect in collagen-fibril processing would impact which layer the most?
Dermis (made of mostly collagen and elastic fibers)
55
What cytoskeletal structure would be most prevalent on a melanocyte?
Hemidesmosomes
56
What layer of skin would be the most likely origin of skin cancer?
Stratum basale
57
What 2 molecules provide sealant b/w adjacent cells in epidermis?
1. Lipids | 2. Glycolipids
58
Where are cells that produce pigment for dark hair located?
Hair matrix
59
What separates hair follicles from the connective tissue of the dermis?
Glassy membrane
60
What type of connective tissue is reticular dermis comprised of?
Dense irregular connective tissue
61
What cells aid eccrine sweat glands in their secretory process?
Myoepithelial cells
62
What cells share the same specific epidermal layer as Merkel cells?
Basal stem cells for keratinocytes
63
T/F: vellus hair is present on most skin of the human body
True
64
T/F: merocrine and apocrine sweat glands simple tubular coiled glands
True
65
What are 2 special variants of loose connective tissue?
1. adipose tissue | 2. reticular connective tissue
66
T/F: mucous connective tissue is common in adult ind's
False
67
How long does renewal of human epidermis thru mitotic activity take?
3-4 wks
68
What color are basal cell carcinomas on slides and why?
- big blue balls in the dermis | - b/c they are derived from basal cells, which appear blue on slides
69
From which type of cell do basal and squamous cell carcinomas originate?
Keratinocytes
70
Genes assoc w/ UV-related melanoma? (2)
BRAF and RAS
71
Gene associated w/ familial melanoma?
CDKN2A
72
Genes assoc w/ basal cell carcinoma? (2)
PTCH and SMO
73
Gene assoc w/ squamous cell carcinoma?
p53
74
Describe epidermodysplasia verruciformis (Treeman syndrome) (3)
- increased susceptibility to HPV - high risk for skin cancer - growth of verrucae (warts) of hands and feet
75
Genes assoc w/ EV syndrome and functions? (2)
- EVER1 and EVER2 | - supposed to regulate zinc, a cofactor for viral proteins that they limit access to by viruses
76
Most common form of skin cancer?
Basal cell carcinoma
77
Major diff in skin lesions from squamous vs basal cell carcinoma?
- squamous = crusty appearance of papules | - basal = pearly appearance of papules
78
ABCDE of melanoma?
- Asymmetric pattern - Borders are irregular - Color is not uniform - Diameter>6mm - Evolution/growth over time
79
Common melanoma in older pts w/ very slow growth rate?
- Lentigo maligna melanoma | - good prognosis
80
Most common melanoma in dark skinned pts?
- Arcal lentiginous melanoma | - poor prognosis
81
Precancerous condition that could lead to squamous cell carcinoma?
Actinic keratosis
82
Gene defects implicated in epidermolysis bullosa simplex? (2)
Keratins 5 and 14
83
Presentation of Epidermolysis bullosa simplex? (2)
- blisters on hands/feet | - blisters are w/i basal layer
84
What disease: | autoimmune blistering disease where keratinocytes can't connect to one another?
Pemphigus vulgaris (spec attacks cells in stratum spinosum)
85
Brief mechanism of Pemphigus vulgaris?
IgG autoantibodies against desmogleins (Dsg) 1 and 3
86
Presentation of Pemphigus vulgaris? (3)
- eroding skin - cornflake like appearance - ulcers
87
What is Nikolsky's sign? (2)
- epidermis sep's when you manually stroke skin | - sign of a serious blistering disease
88
Histo presentation of PV? (3)
- intra-epidermal cleft w/i stratum spinosum - acantholysis - net-like pattern under immunofluorescence of Ab's
89
Bullous pemphigoid is autoimmune disorder affecting what 2 genes and what protein?
- BPAG1 or BPAG2 | - hemidesmosomal proteins
90
Histo effects of Bullous pemphigoid? (2)
- split underneath basal cells | - linear immunofluorescence band @ DEJ
91
Symptoms of Bullous pemphigoid?
- fluid-filled blisters | - this shows blister is below epidermis
92
What protein affected by Dystrophic epidermolysys bullosa?
- inability to make Collagen 7 (anchoring collagen)

Histology (7 decks)

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