SM_255a: Structure and Function of Skin Flashcards Preview

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Flashcards in SM_255a: Structure and Function of Skin Deck (40)
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1

Skin functions include ____, ____, ____, ____, ____, and ____

Skin functions include barrier, repair, immunologic, sensation, thermoregulation, and appearance

 

  • Barrier: resist mechanical stress, limit water loss from inside, block entry from outside, UV shield
  • Repair: wound healing
  • Immunologic: temper and alert immune system
  • Sensation: pain, itch, pressure
  • Thermoregulation, insulation, and absurption
  • Appearance: quality of life

2

Skin layers from outermost to innermost are ____, ____, and ____ and appendages include ____, ____, ____, and ____

Skin layers from outermost to innermost are epidermis, dermis, and hypodermis and appendages include hair, sebaceous glands, sweat glands, and nails

3

Epidermis is ____

Epidermis is keratinizing stratified squamous epithelium

4

Dermis is ____

Dermis is connective tissue/stroma

5

Dermis includes the ____ and ____

Dermis includes the outer papillary dermis and inner reticular dermis

6

Epidermis is ____, while the dermis ____

Epidermis is avascular, while the dermis is vascular

7

Describe the layers of the epidermis from bottom up

Layers of the epidermis from bottom up

  1. Basal layer (stratum basale): proliferation/anchorage - E-cadherin
  2. Spinous layer (stratum spinosum): adhesion - demososomes
  3. Granular layer (stratum granulosum): differentiation
  4. Cornified layer (stratum corneum): death

8

Epidermal cell layers are ____

Epidermal cell layers are morphologically distinct

9

____ are the major cell type in the epidermis

Keratinocytes are the major cell type in the epidermis

 

 

(keratinocytes exist in various states of proliferation and differentiation in epidermis)

10

In addition to keratinocytes, ____, ____, and ____ are found in the epidermis

In addition to keratinocytes, Langerhans cells, melanocytes, and Merkel cells are found in the epidermis

 

  • Langerhans cells: dendritic antigen presenting cells
  • Melanocyte: pigment-producing cells
  • Merkel cells: mechanoreceptor

11

Epidermis functions primarily to build a ____ in order to ____, ____, ____, and ____

Epidermis functions primarily to build a semi-permeable barrier in order to resist physical trauma and repair wounds, prevent entry of noxious agents (outside-in barrier), limit excessive water loss (inside-out barrier), and protect against UV irradiation from sun

12

Epidermis building involves replenishing to ____

Epidermis building involves replenishing to maintain a constant supply of keratinocytes to repopulate upper layers

  • Stem cells in the basal layer give rise to proliferating compartment
  • Basal layer cells exit cell cycle and replenish upper layer
  • Outermost cells are constantly sloughed off
  • Epidermis turns over every 30 days

13

Psoriasis is an ____ skin disease that involves ____, ____, and ____

Psoriasis is an inflammatory skin disease that involves increased keratinocyte proliferation and turnover, abnormal differentiation, and formation of thick scaly plaques

14

Epidermis building involves resisting which is accomplished by ____

Epidermis building involves resisting which is accomplished by specialized structures to yield a strong cell

  • Keratinocytes maintain shape by building cytoskeleton networks: microtubules, actin-based microfilaments, keratin-based intermediate filaments
  • 54 different human keratins pair up to form intermediate filaments
  • Keratins are major protein in keratinocytes
  • Keratin composition changes as keratinocytes differentiate

15

____ are responsible for maintaining shape of the epidermis by building cytoskeleton networks

Keratinocytes are responsible for maintaining shape of the epidermis by building cytoskeleton networks

16

Keratins ___ and ___ are expressed in the basal layer, while keratins ___ and ___ are expressed in the spinous and granular layers

Keratins 5 and 14 are expressed in the basal layer, while keratins 1 and 10 are expressed in the spinous and granular layers

17

____ occurs due to issues with keratin 5 and 14 in the basal layer

Epidermolysis bullosa simplex occurs due to issues with keratin 5 and 14 in the basal layer

18

____ occurs due to issues with keratin 1 and 10 in the spinous and granular layers

Epidermolytic ichthyosis occurs due to issues with keratin 1 and 10 in the spinous and granular layers

19

____ anchored to the ____ attach the epidermis to the underlying dermis

Keratinocytes anchored to the underlying dermis attach the epidermis to the underlying dermis

20

____ are integrin-based junctions that connect basal keratinocytes to the basement membrane

Hemidesmosomes are integrin-based junctions that connect basal keratinocytes to the basement membrane

21

____ occurs due to mutations in hemidesmosome gene COL17A1

Junctional epidermolysis bullosa occurs due to mutations in hemidesmosome gene COL17A1

22

____ occurs due to autoantibodies against collagen 17, which ____

Bullous pemphigoid occurs due to autoantibodies against collagen 17, which breaks the connection between basal keratinocytes and basement membrane

23

____ are specialized junctions that anchor keratin to sites of cell-cell contact

Desmosomes are specialized junctions that anchor keratin to sites of cell-cell contact

24

____ occurs when autoantibodies target proteins found in desmosomes, ____

Pemphigus vulgaris occurs when autoantibodies target proteins found in desmosomes, breaking the connection between adjacent keratinocytes

25

26

____ made of ____ allow for selective permeability in the epidermis

Tight junctions made of occludin allow for selective permeability in the epidermis

27

Stratum corneum can be likened to ____

Stratum corneum can be likened to bricks and mortar

 

  • Bricks -> corneocytes: anucleate, keratin-filled, dead keratinocytes encased in a highly crosslinked specialized membrane - the cornified envelope
  • Mortar -> lamellar membrane: lipids (ceramides, cholesterol, and free fatty acids) extruded from keratinocytes to form a hydrophobic seal

28

____ is caused by defects in lipid transport in the epidermis

Harlequin ichthyosis is caused by defects in lipid transport in the epidermis

 

(mutation in ABCA12 gene)

29

____ is caused by defects in cornified envelope production

Lamellar ichthyosis is caused by defects in cornified envelope production

 

(mutation in TGM1 gene)

30

Strategies for building for a barrier include ____, ____, ____, and ____

Strategies for building for a barrier include replenish, resist, repel, and reside

  • Replenish: maintain a constant supply of keratinocytes to repopulate upper layers
  • Resist: adopt specialized structures to yield a strong sticky cell
  • Repel: form an impermeable seal (fence and gate barrier), extrude lipids and cornified envelope
  • Reside: exist in a space that provides tough flexible support and nutrient/gas exchange

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