Jain Chapter 1 - Basic Science Flashcards

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1
Q

What has developed by 3-4 weeks gestational age?

A

Single layer of ectoderm

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2
Q

What has developed by 6 weeks gestational age?

A

Outer flattened periderm and inner, cuboidal germinal (basal) layer

Germinal layer in contact w/ underlying mesenchyme (germinal layer produces entire epidermis)

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3
Q

What has developed by 7 weeks gestational age?

A

*Fetal basement membrane

Tooth primordia

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4
Q

What has developed by 8-12 weeks gestational age?

A

Epidermal stratification begins ~8 weeks (Completed by 2nd trimester)

*Appearance of Melanocytes, Langerhans cells, Merkel cells

Dermal-subcutaneous boundary distinct

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5
Q

What has developed by 9-12 weeks gestational age?

A

Appearance of anchoring filaments/hemidesmosomes

Hair follicle and nail primordia seen

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6
Q

What has developed by 12 weeks gestational age?

A
  • Formation of dermoepidermal junction (DEJ)
  • Nail bed starts to keratinize, proximal nail fold forms

Type III collagen appears

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7
Q

What has developed by 12-14 weeks gestational age?

A

Parallel ectodermal ridges (fingerprints)

Eccrine and sebaceous gland primordia seen

Fibroblasts actively synthesizing collagen and elastin in dermis

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8
Q

What has developed by 12-24 weeks gestational age?

A

Melanin production (12–16 wks), melanosome transfer (20 wks)

Hair follicles differentiate during 2 nd trimester (7 concentric layers present)

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9
Q

What has developed by 15-20 weeks gestational age?

A

Periderm is shed (periderm is part of vernix caseosa) [20–21 weeks]

*Follicular keratinization, nail plate completely covers nail bed

Papillary/reticular boundary distinct, dermal ridges appear

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10
Q

What has developed by 22 weeks gestational age?

A

Trunk eccrine gland primordia

Elastic fiber seen

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11
Q

What has developed by 22-24 weeks gestational age?

A

*Mature epidermis complete (w/ interfollicular keratinization)

Adipocytes appear under dermis

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12
Q

How thick is:

  • eyelid skin
  • palmoplantar skin
A

eyelid = 0.04 mm

palmoplantar skin = 1.5

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13
Q

Keratinocytes comprise approximately ___ of epidermal cells

A

80–85%

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14
Q

Total epidermal turnover time

A

Average 45–60 days (30–50 days from stratum basale to stratum corneum and approximately 14 days from stratum corneum to desquamation)

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15
Q

Epidermal self-renewal maintained via stem cells in basal layer of ___ epithelium and the bulge region of hair follicles (latter location only activated with epidermal injury)

A

interfollicular

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16
Q

Keratinocytes produce ___

A

keratin filaments (syn: intermediate filaments or tonofilaments), which form the cell’s cytoskeletal network; this provides resilience, structural integrity, along with serving as a marker for differentiation (ie. basal layer: K5/14)

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17
Q

Type I (acidic) epithelial keratins

A

K9–28, chromosome 17

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18
Q

Type I (acidic) hair keratins

A

K31–40 (old nomenclature: hHa1–hHa8, Ka35, Ka36)

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19
Q

Type II (basic) epithelial keratins

A

K1–8 and K71–80, chromosome 12

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20
Q

Type II (basic) hair keratins

A

K81–86 (old nomenclature: hHb1–hHb6)

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21
Q

Location of expression and disease: 1 & 10

A

Suprabasal keratinocytes

Epidermolytic hyperkeratosis, UnnaThost PPK

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22
Q

Location of expression and disease: 1 & 9

A

Palmoplantar suprabasal keratinocytes

Vorner PPK

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23
Q

Location of expression and disease: 2e & 10

A

Granular and upper spinous layer

Ichthyosis bullosa of Siemens

24
Q

Location of expression and disease: 3 & 12

A

Cornea

Meesman corneal dystrophy

25
Q

Location of expression and disease: 4 & 13

A

Mucosal epithelium

White sponge nevus

26
Q

Location of expression and disease: 5 & 14

A

Basal keratinocytes
Dowling-Degos disease, EBS

(Do not confuse Dowling-Degos with Degos disease: Dowling-Degos: AD, reticulated pigmentation over skin folds Degos (malignant atrophic papulosis): occlusion + tissue infarction)

27
Q

Location of expression and disease: 6a & 16

A

Outer root sheath

Pachyonychia congenita I

28
Q

Location of expression and disease: 6b & 17

A

Nail bed

Pachyonychia congenita II

29
Q

Location of expression and disease: 8 & 18

A

Simple epithelium

Cryptogenic cirrhosis

30
Q

Location of expression and disease: K81 K86

A

Hair

Monilethrix

31
Q

Location of expression and disease: 19

A

Stem cells

32
Q

Stratum Basale (Germinativum)

  • What % are stem cells?
  • Expression of ___, which is a marker for proliferative activity
  • De novo expression of ___ occurs, forming keratin filaments which insert into both desmosomes and hemidesmosomes and form keratinocyte cytoskeleton
A
  • 10%
  • ornithine decarboxylase (ODC)
  • K5/14
33
Q

Ornithine decarboxylase (ODC)

  • Stimulated by?
  • Blocked by?
A
  • stimulated by UVB

- partially blocked by retinoic acid/corticosteroid/vitamin D3

34
Q

Stratum Spinosum

  • New synthesis of ___; K5/14 still present (not de novo)
  • Cells contain ___
A
  • K1/K10

- lamellar granules (lamellated bodies or odland bodies)

35
Q

Desmosomes

  • Transmembrane proteins
  • Desmosomal plaque proteins
A
  • Transmembrane proteins: desmoglein 1/3, desmocollin 1/2 (desmosomal cadherins)
  • Desmosomal plaque proteins: plakoglobin (γ-catenin), desmoplakin 1/2, keratocalmin, desmoyokin, band 6 protein, envoplakin
36
Q

Adherens junctions

  • What kind of cell junction?
  • Linked to?
A
  • classical cadherins (namely E and P)

- linked to actin cytoskeleton via cytoplasmic plaque proteins (α, β, γ-catenin)

37
Q

Gap junctions

- transmembrane channels formed by six ___ monomers

A
  • connexin
38
Q

Tight junctions

- major constituents are?

A
  • claudins and occludins
39
Q

Gap junction - Connexin 26 diseases

A
  • Vohwinkel syndrome
  • PPK + deafness
  • KID syndrome
40
Q

Gap junction - Connexin 30 diseases

A

Hidrotic ectodermal dysplasia (HED)

41
Q

Gap junction - Connexin 31/30.3 diseases

A

Erythrokeratoderma variabilis (EKV)

42
Q

Adherens junction diseases - b-catenin

A

Muscular dystrophy

43
Q

Hemidesmosome diseases - a6b4

A
  • Junctional EB with pyloric atresia

- Occular CP

44
Q

Hemidesmosome diseases - Plectin

A
  • EB simplex with muscular dystrophy

- PNP

45
Q

Hemidesmosome diseases - BPAG1 (BP 230)

A
  • Bullous pemphigoid (BP)

- PNP

46
Q

Hemidesmosome diseases - BPAG2 NC16A (BP 180)

A
  • BP
  • Pemphigoid gestationis
  • LABD
47
Q

Hemidesmosome diseases - BPAG2 COOH (BP 180)

A

CP

48
Q

Desmosome diseases - Plakoglobin

A

Naxos syndrome

49
Q

Desmosome diseases - Desmoplakin

A

Carvajal syndrome

50
Q

Desmosome diseases - Plakophilin

A

Ectodermal dysplasia (ED) + with skin fragility

51
Q

Desmosome diseases - Desmocollin

A

Subcorneal pustular dermatosis (SCPD)

52
Q

Desmosome diseases - Desmoglein 1

A
  • Pemphigus foliaceous, (PF)
  • striate PPK
  • PNP
  • also target for SSSS
53
Q

Desmosome diseases - Desmoglein 3

A
  • Pemphigus vulgaris (PV)

- PNP

54
Q

Hemidesmosome diseases - K5&14

A
  • EBS
55
Q

Hemidesmosome diseases - 322

A
  • JEB intermediate and severe
  • anti-epiligrin
  • CP
56
Q

Hemidesmosome diseases - collagen 7

A
  • Bullous SLE
  • DEB
  • EBA