Photobiology and Photosensitive dermatoses Flashcards Preview

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Flashcards in Photobiology and Photosensitive dermatoses Deck (31):
1

What is included in optical radiation?

UV, visible light and infrared

2

UV radiation exists at wavelengths above/below that of visible light

below

3

What are the ranges of wavelengths for UVA, UVB, and UVC light?

UVA--> 320-400
UVB--> 280-320
UVC--> 200-280

4

What UV radiation causes aging?

UVA

5

What is minimal erythema dose (MED)

the minimal amount of a particular wavelength of light capable of causing redness of the skin

6

The effect of absorption depends on the _______, the molecule that absorbs light energy in the skin

Chromophore

7

a chromphore can absorb what kind of light rays?

UVA, UVB or both

8

What effects does UV light have on DNA?

UVB suppresses DNA synthesis which mediates anti-inflammatory effects on the skin

9

What effects does UV light have on melanin?

stimulates the melanocyte

10

What effects does UV light have on protein?

collagen and elastic fiber degeneration---> results in photoaging

11

What are often treated by laser therapies?

dyschromia and pigmented skin lesions
telangiectasias
vascular neoplasms

12

lasers that target water are specifically used for what kind of pathology?

warts

13

What is a Fitzpatrick skin type IV?

never burns always tans

14

What is a Fitzpatrick skin type V

moderately pigmented skin

15

What does Immediate tanning result from ?

UVA exposure from the oxidation of melanin

16

What does Delayed tanning result from?

UVA and UVB exposure--> increased # of melanocytes, increased melanin synthesis and increased association of melanosomes with keratinocytes

17

What are the pro-inflammatory properties of UV exposure?

sunburns, phototoxic and photoallergic reactions

18

What are the anti-inflammatory properties of UV exposure?

used to treat dieases like psoriasis and atopic dermatitis

19

Describe some common features of phototoxic reactions

Manifested by redness, swelling, and burning/stinging
sun-protected sites are spared
onset within 24 hours
NOT immune related so may occur upon first exposure

20

What is Phytodermatisis?

occurs following exposure to caustic plant material coupled with UV light
plants may contain furocoumarins which is a photosensitizer

21

What is the differences between phototoxic reactions and photoallergic?

Photoallergic has delayed onset because it is immune related
Photoallergic has redness and itching
Phototoxic has redness, swelling and burning/stinging

22

What is a common causative agent of photoallergic reactions

sulfa drugs

23

What is the clinical presentation of PMLE

itching, edema, pink, papules coalescing into plaques and vesicles of sun-exposed skin

24

What is the treatment of PMLE?

avoid sun, topical corticosteroids, and possible phototherapy

25

What are some common features of XP

autosomal recessive
caused by impaired DNA nucleotides excision repair
30% risk to develop neurologic abnormalities

26

What is the phototherapy recommendation for psoriasis?

narrow band UBV (311nm)

27

What is psoralen?

medication that increases the absorption of UV light and the subsequent anti-inflammatory properties (most often used with UVA)

28

what are examples of physical blockers of sunscreen?

zinc oxide and titanium dioxide

29

What are UVA blockers?

Benxophenones
Avobenzone
Mexoryl
Titanium dioxide/Zinc oxide

30

What are UVB blockers?

PABA
Padimate O
Salicylates
Cinnamates
Titanium dioxide/ zinc oxide

31

What is SPF?

The ratio of time development of minimal erythema dose compared to the onset of erythema in unprotected skin
SOLELY DUE TO UVB EXPOSURE