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Derm > UV Exposure > Flashcards

UV Exposure Flashcards

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Dermatology Board Prep flashcards
1
Q

WHat are the divisions of the UV spectrum

A

UVA (320 - 400 nm)
UVB (290 - 320 nm)
UVC (200 - 290 nm)

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2
Q

What is the most potent of all UVR?

A

UVC (200 - 290 nm)

  • is abs by DNA, RNA, and proteins and is lethal to epidermal cells
  • ** OZONE FILTERS OUT UVC COMPLETELY (well is supposed to…)
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3
Q

The ozone is important for our protection from

A

UVC and VVB

i.e. UVC should not be able to penetrate atmosphere and very little UVB should

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4
Q

What type of light causes sunburn?

A

UVB

** hinted to know this

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5
Q

Window glass filters out wavelengths less than _____. What is the significance of this?

A

320

ie. UVB filtered

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6
Q

SPF is based of off UV__

A

B

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7
Q

What type of light is responsible for “photo aging”

A

UVA

*UVB is more efficient at it but there is a higher conc of UVA + it penetrates deeper

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8
Q

Factors that modify composition and intensity of UVR at earths surface

A 
Coud Cover
Time of day
Atmosphere
Reflection (surface)
Season
Altitude
Latitude
Solar flare
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9
Q

95% of UVR reaching earth’s surface is ____ and the remaining is ____

A 
95% = UVA 
2-5% = UVB
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10
Q

UVA or UVB penetrates skin more deeply

A

UVA (even though it has the least amt of energy/bigger wavelength)

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11
Q

What surfaces reflects more than avg?

A

water, sand, FRESH SNOW

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12
Q

T or F: cloud cover protects you from UVR

A

F: it scatters it but does not abs it but you can still get UVB/burns

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13
Q

What type of UVR would hit vessels in the dermis

A

UVA

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14
Q

What is an “action spectrum”

A

certain reaction caused by a specific wavelength

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15
Q

What are chromophores

A

molecules that abs UVR to determine action spectrum responses

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16
Q

What is the major UVB chromophore in skin?

A

DNA

** hinted to know this

17
Q

What is the action spectrum that causes burns? Used for the treatment of psoriasis?

A

300 nm
310 nm

** not imp to know number but should know that diff wavelengths have different effects/action spectrums

18
Q

What are the skin phototypes?

A

types I-VI
I = always burn and never tans
VI = always tans and rarely burns

19
Q

What are acute effect of UVR on skin?

A

“IT DIED” from a sunburn

Inflammation
Tanning
DNA damage
Immunomodulation 
Epidermal Hyperplasia 
vit D synthesis
20
Q 
Why are sunburns...
Red?
Hot?
Swollen?
Painful?
Itchy?
A 
red = vasodilation
Heat = increased blood flow
swelling = secondary to vasopermeability
Pain = cytokines
Itchy = cytokines
21
Q

What are the “sunburn cells” (aka the ones damaged by acute UVR)

A

keratinocytes

22
Q

What are the differences between immediate tanning response and delayed tanning response?
Causes?
Time frame?
protection?

A

immediate is caused by UVA and delayed is UVB

immediate is due to oxidation and redistribution of existing melanin and delayed is due to increased melanin synthesis and transfer

immediate fades w/in 1 hr and delayed is visible after 72 hrs and last for weeks

immediate is not protective and delayed is photoprotective

23
Q

What are the chronic effects of UVR on skin

A

photoaging and photo-carcinogenesis

24
Q

Histological changes with chronic UVR on skin?

A

dermis is more blue bc collagen and elastin is damaged

25
Q

How is chronological aging of skin different than photoaging of skin?

A

chronologic = smooth, pale, finely wrinkled

photo= dry, deep wrinked, inelastic, leathery, irregular pigmentation, telangiectasias

26
Q

solar lentigines

A

“age spot” due to chronic UVR exposure

27
Q

Poikiloderma

A

reticulate hyperpigmentation, telangiectasia and mild atrophy

28
Q

cyst and comedone formation

A

assc with chronic UVR

when seen with yellow thickening of skin with nodules = Favre-Racouchot syndrome

29
Q

DNA is damaged mostly by UVA or UVB

A

UVB

*bases abs photons

30
Q

What are DNA photoproducts

A

dimers formed by covalent binding of 2 adjacent pyrimidines (C and T)

  • cyclobutane dimers
  • 6, 4 photoproducts
31
Q

What are the innate defense mechanisms against UVR?

A 
stratum corneu, reflects UVR
melanin abs UVR
Nucleotide excision repain 
apoptosis 
Tumor supressor genes (p53, PTCH)
32
Q

Heritable disease characterized by marked sensitivity to UV radiation, see evidence of photo damage much earlier in life (freckles, wrinkles, skin atrophy)

A

xeroderma pigmentosum

33
Q

What causes XP?

A

defect in DNA repair mech (usually a step in NT excision repair)

34
Q

WHat are consequences/effects of XP?

A
  • get skin cancers very early in live (<10 yo)
  • Eyes: cataract, corneal scaring, dryness, aging and degeneration
  • CNS: neurologic degeneration
35
Q

Describe the effect of UVR on the immune system

A

ImmunoSUPPRESSIVE effects:

  • langerhan cells disappear from kin following mild sunburn
  • lymphocytes are also sensitive
36
Q

What skin conditions can be treated with light? Why?

A

psoriasis
cutaneous lymphoma
eczema

due to immunosuppresive effects of UVR

37
Q

What type of UVR do tanning beds primarily emit?

A

UVA

**5X the amt/unit time than solar UVA

38
Q

T or F: tans from a tanning bed is just as protective as one from UVB sunlight

A

F: 10x less protective

Derm (12 decks)

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