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Dermatology 1 > Skin function, epidermis > Flashcards

Skin function, epidermis Flashcards

(58 cards)

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1
Q

skin as physical barrier (3)

A
  • prevention of water, electrolyte, macromolecule loss
  • prevention of invasion by external agents (chemical, physical, microbial)
  • anatomic (atratum corneum, hair)
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2
Q

skin as physiologic barrier (2)

A
  • turnover rate (30-45 days for keratinocyte to go from basal layer to surface)
  • sebum (bacteriostatic, fungistatic)
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3
Q

skin as immunologic barrier

A

-keratinocytes, langerhans cells (macrophages), and lymphocytes provide the skin with an immunosurveillance capability that effectively protects against the development of cutaneous neoplasms and persistent infections

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4
Q

skin microbial flora

A
  • normal bacteria inhibit the growth of pathogens and compete with pathogens for nutrients/space
  • fungal, viral phyla protect skin against pathogens
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5
Q

skin and communication

A
  • sensory: primary sense organ for touch, pressure, pain, itch, heat, cold
  • immunologic: langerhans cells present antigen to lymphocytes in regional lymph nodes
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6
Q

skin and temperature regulation (4)

A
  • hair coat
  • cutaneous blood supply
  • subcutaneous fat
  • sweat glands (horses - apocrine, dogs/cats - eccrine in footpads)
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7
Q

skin and secretion

A

secretory organ by virtue of apocrine, eccrine, and sebaceous glands

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8
Q

skin and storage

A

reservoir of electrolytes, water, vitamins, fat, carbs, proteins, and other materials

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9
Q

skin and pigmentation

A
  • melanin formation, vascularization, and keratinization help determine the color of the skin/coat
  • pigmentation protects from solar radiation damage (UV light)
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10
Q

skin and vitamin D production

A

vitamin D produced in skin through stimulation by solar radiation

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11
Q

akin and adnexa production

A

skin produces keratinized structures such as hairs, nails, claws, hooves, and the horny layer of the epidermis

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12
Q

skin as an indicator

A

may be an indicator of general health and internal diseases

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13
Q

skin and motion/shape

A
  • flexibility, elasticity, and toughness allow motion, provide shape and form
  • many species differences as to structure and function of skin
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14
Q

4 main skin regions

A
  • epidermis
  • dermal-epithelial junction
  • dermis
  • hypodermis/subcutaneous tissue
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15
Q

what are epidermally derived appendages

A
  • hair follicles
  • sebaceous glands
  • apocrine sweat glands
  • eccrine sweat glands
  • nails/claws/hooves
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16
Q

layers of the epidermis (inner to outer)

A
  • stratum basale (basal layer)
  • stratum spinosum (spinous layer)
  • stratum granulosum (granular layer)
  • stratum lucidum (clear layer)
  • stratum corneum (horny layer)
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17
Q

cells in basal layer

A

cuboidal cells called keratinocytes (90%), melanocytes (10%), and merkel cells (1%)

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18
Q

what is important about basal layer

A

site of cell division (mitosis)

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19
Q

how are basal cells attached to basement membrane zone

A

hemidesmosomes

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20
Q

cell to cell attachments in basal layer - what are they?

A

desmosomes (in between keratinocytes): junctions which can breakdown and reform to allow other cells to pass between keratinocytes and allow keratinocytes to move upward in epidermis to become keratinized and form stratum corneum

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21
Q

why are desmosomes important to us

A

they are the target antigen for the most common autoimmune skin diseases of domestic species called pemphigus foliaceus (also the target antigen for other forms of pemphigus)

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22
Q

what is stratum spinosum composed of

A

the daughter cells of the stratum basale

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23
Q

layers in stratum spinosum

A
  • number of layers varies between species and within the animal
  • tends to be 1-3 layers thick in hairy skin
  • thickest layer of the skin
  • thicker in footpads, nasal planum, and mucocutaneous junctions (20 layers)
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24
Q

cells in stratum spinosum (structure)

Study These Flashcards
A
  • polyhedral in shape

- “prickle cells” have desmosomes

25
what do cells of the stratum spinosum do
- start the process of differentiation to become completely keratinized - synthesize proteins that will be part of the cornified cell envelope and the membrant coating granule, which produce the lipids that will form the intercellular lipid lamellae
26
what is acanthosis and what can cause it abnormally
- an increase in thickness of the stratum spinosum | - chronic inflammatory processes can result in it
27
granular layer layers
- variably present in haired skin (1-2 layers) | - thicker in hairless skin
28
keratinocytes in stratum granulosum
- flattened in this layer | - contain keratohyalin granules --> keratinization process, barrier function
29
other products of granular layer keratinocytes
membrane coating granules --> produce the lipid in the intracellular spaces of stratum corneum
30
what cells does stratum lucidum contain
fully cornified flat cells (non-staining)
31
where is stratum lucidum present
only in areas of friction and areas where the epidermis is thick
32
what is stratum corneum composed of
several layers of flattened, anuclear fully cornified cells arranged in vertical columns
33
another name for keratinocytes in stratum corneum
corneocytes
34
what are intracellular spaces of stratum corneum filled with
lamellar lipids
35
function of stratum corneum
- skin barrier/protective functions | - cornified cells envelope composed of cross-linked proteins and provide structural support, resist invasion
36
what does stratum corneum constitute
the major barrier of the epidermis --> "brick wall"
37
define: hyperkeratosis
increase in thickness of stratum corneum
38
what is most abundant cell in epidermis
keratinocyte (called corneocytes in stratum corneum)
39
origin and location of keratinocytes
- origin: ectoderm | - location: throughout epidermis
40
functions of keratinocytes (3)
- production of keratin - production of intracellular lamellar lipid (stratum corneum) - epidermal immunity (cytokines, defensins)
41
what are defensins
- produced by keratinocytes in dermis | - make holes in wall of bacteria, viruses, protozoa (epidermal immunity)
42
what are melanocytes
- dendritic cells (no immune function) in epidermis | - appear clear on H&E, long dendritic processes
43
origin and location of melanocytes
- origin: neural crest | - location: basal layer of epidermis, hair follicles, ducts of sebaceous/apocrine glands
44
functions of melanocytes (2)
- production of melanin (coloration, UV protection) | - communication with keratinocytes
45
what are langerhans cells
- epidermal dendritic cells | - clear cells on H&E --> "tennis racket" granules (birbeck granules)
46
origin and location of langerhans cells-
- origin: bone marrow | - location: suprabasal layers of epidermis
47
functions of langerhans cells (3)
- immune surveillance - antigen processing and presentation - development of allergic dermatitis and graft rejection
48
what epidermal cells are positive for Thy 1 antigen
NK cells
49
what are merkel cells
-pidermal clear cells confined to stratum basale of tylotrich pads
50
origin and function of merkel cells
- origin: neural crest or ectoderm | - function: slow adapting mechanoreceptors
51
what other cells are present in epidermis transiently in diseased states - how are they present
- neutrophils, eosinophils, lymphocytes, erythrocytes | - process: exocytosis (inflammatory process)
52
what other epidermal cells are present in most mammals and participate in skin immunologic barrier
gamma-delta T cells
53
3 stages of epidermis life cycle
mitosis, differentiation, exfoliation
54
is normal desquamation usually visible or not
rarely visible
55
what does the shedding of visible scale indicate and why
- indicates a disorder of keratinization (inflammation) - more basal keratinocytes are undergoing mitosis, therefore more differentiate, keratinize, and turnover faster (basal cells become keratinized faster)
56
haired skin info
- thin epidermis and thin stratum corneum - slightly undulating but without rete pegs - thickness varies within species according to the area of the body
57
glabrous/unhaired skin info
- epidermis and stratum corneum are thicker | - prominent rete pegs protrude into dermis
58
in general, where is the skin thickest and thinnest
- thickest over dorsum and neck | - thinnest over ventrum, axillae, inguinal regions

Dermatology 1 (4 decks)

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