Chapter 1- Epidermis Flashcards

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1
Q

Name the four distinct cell types within the epidermis

A
  1. Keratinocytes 2. Melanocytes 3. Langerhans cells 4. Merkel cells
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2
Q

Keratinocytes compose what percentage of epidermal cells?

A

85%

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3
Q

Melanocytes compose what percentage of epidermal cells?

A

5%

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4
Q

Langerhans cells compose what percentage of epidermal cells?

A

3 to 8%

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5
Q

Merkel cells compose what percentage of epithelial cells?

A

2%

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6
Q

The epidermis is divided into 5 layers. Name them from inner to outer

A
  1. basal layer (Stratum basale) 2. spinous layer (stratum spinosum) 3. granular layer (stratum granulosum) 4. clear layer (stratum lucidum) 5. horny layer (stratum corneum)
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7
Q

The epidermis of cats and dogs in haired skin is how many nucleated cell layers (not counting the horny layer)?

A

2 to 3

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8
Q

The haired epidermis of cats and dogs is how thick? (range)

A

0.1 to 0.5 mm

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9
Q

Where is the thickest epidermis found and how thick does it measure there?

A

footpads and nasal planum- 1.5 mm

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10
Q

The footpad epidermis is smooth in dogs or cats? Papillated and irregular in dogs or cats?

A

Cats- smooth; Dogs- papillated and irregular

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11
Q

Projections of the epidermis into the underlying dermis are called____ ______.

A

rete ridges

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12
Q

What are rete ridges?

A

projections of the epidermis into the underlying dermis

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13
Q

Where are rete ridges NOT found?

A

they are NOT found in the normal hair bearing skin of cats and dogs

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14
Q

Where are rete ridges found?

A

foot pad, nasal planum epidermis, scrotum

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15
Q

Name the cell types that compose the stratum basale

A

single row of columnar to cuboidal cells

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16
Q

Where do the columnar and cuboidal cells of the stratum basale rest upon? (what structure)

A

basement membrane

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17
Q

Basement membrane separates what two layers?

A

dermis from the epidermis

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18
Q

The columnar and cuboidal cells of the stratum basale are mostly what distinct cell type?

A

keratinocytes

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19
Q

The keratinocytes in the basal layer are constantly reproducing and pushing in which direction to replenish epidermal cells?

A

upward

20
Q

There is morphologic and functional heterogenicity in what kind of keratinocytes (a layer)

A

basal keratinocytes

21
Q

Describe the different functions of the different populations of basal keratinocytes

A
  1. anchor the epidermis 2. serve as a proliferative and reparative (stem cell) function
22
Q

Keratinocyte differentiation is AKA

A

keratinization

23
Q

Define keratinization

A

A genetically programmed complex series of metabolic events and morphologic changes

24
Q

Cells of the stratum basale contain which keratin filaments?

A

K5 and K14

25
Q

K5 and K14 keratin filaments attach to neighboring cells through _______ and to the basement membrane zone at _______

A

desmosomes; hemidesmosomes

26
Q

The major cell adhesion junction of epithelial tissues is called ______.

A

desmosomes

27
Q

Desmosomes provide the anchor for intermediate filaments connecting ___ to ______; They also anchor ________cells together

A

nuclear envelope to the cell membrane; adjacent cells together

28
Q

This major cell adhesion junction stabilizes the structure of the _____.

A

epidermis

29
Q

The molecular components of the desmosome belong to what 3 major gene families?

A
  1. plakins 2. armadillo proteins 3. desmosomal cadherins
30
Q

Plakins, armadillo proteins, and desmosomal cadherins are a common target for what?

A

many diseases

31
Q

What are hemidesmosomes?

A

Junctional complexes distributed along the inner aspect of basal keratinocytes

32
Q

What is the major role of hemidesmosomes?

A

epidermal-dermal adhesion

33
Q

Various inherited defects in the hemidesmosome-anchoring filament components are known to produce what 3 diseases?

A
  1. epidermolysis bullosa 2. pemphigoid 3. bullous systemic lupus erythematosus
34
Q

What are integrins?

A

A large family of cell surface adhesive receptors

35
Q

Integrins are important in what type of interactions?

A

cell-cell and cell-matrix interactions

36
Q

Can integrins also act as signal transducers?

A

Yes

37
Q

Each integrin consists of a heterodimer of which two subunits?

A

alpha and beta

38
Q

Are the alpha and beta subunits of integrins covalently or noncovalently associated?

A

noncovalently

39
Q

In the epidermis, integrin expression is normally confined to which layer?

A

basal

40
Q

Which integrin subunits are most abundant in the epidermis?

A

alpha 2, alpha 3, beta 1, alpha 6, beta 4

41
Q

Structural Target: Intermediate Filaments
Molecular Target: K5/K14
Congenital Disease:
Acquired Disease:

A

Congenital Disease: Epidermolysis bullosa simplex

Acquired Disease: Ocular cicatricial pemphigoid

42
Q

Structural Target: Desmosomes
Molecular Target: Desmoglein 1, desmoglein 3
Acquired DIsease:

A

Pemphigus vulgaris, pemphigus foliaceous

43
Q

Structural Target: Desmosomes
Molecular Target: Plakoglobin, desmoplakins
Congenital Disease:
Acquired Disease:

A

Congenital Disease: Ectodermal dysplasia, skin fragility

Acquired Disease: Paraneoplastic pemphigus

44
Q

Structural Target: Hemidesmosome transmembrane molecules
Molecular Target: alpha6Beta4 Integrin
Congenital Disease:
Acquired Disease:

A

Congenital Disease: Junctional epidermolysis bullosa

Acquired Disease: Bullous pemphigoid, mucous membrane pemphigoid

45
Q

Structural Target: Hemidesmosome
Molecular Target: BPAG1e (BP230), collagen XVII (BP180, BAPG2, LAD01)
Congenital Disease:
Acquired Disease:

A

Congenital Disease: Epidermolysis bullosa (humans, collagen XVII)
Acquired: Bullous pemphigoid, mucousmembrane pemphigoid, linear IgA bullous disease

46
Q

Structural Target: Lamina densa (BMZ)
Molecular Target: Laminin
Congenital Disease:
Acquired Disease:

A

Congenital Disease: Junctional epidermolysis bullosa

Acquired Disease: Mucous membrane pemphigoid, acquired junctional epidermolysis bullosa

47
Q

Structural Target: Anchoring fibrils (BMZ)
Molecular Target: Type VII collagen
Congenital Disease:
Acquired Disease:

A

Congenital Disease: Dystrophic epidermolysis bullosa

Acquired Disease: Epidermolysis bullosa acquisita, type 1 bullous systemic lupus erythematosus