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OS Derm > Pathophys-Day 2 Photobiology > Flashcards

Pathophys-Day 2 Photobiology Flashcards

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Dermatology Board Prep flashcards
1
Q

What UV spectrum does the ozone layer block out and what is its wavelength range? Which one is fairly dependent on ozone concentration?

A

UVC, 290-200

UVB dep on ozone [ ]

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2
Q

Which UV spectrum causes sunburn?

A

UVB, 290-320

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3
Q

Which UV spectrum is filtered out by window glass?

A

UVB, 290-320

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4
Q

What does SPF 50 tell you?

A

Would take 50x long to get as burned as without the sunscreen

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5
Q

Does UVA penetrate glass?

A

Yes

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6
Q

UVA range

A

320-400

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7
Q

Which UV is the least potent?

A

UVA

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8
Q

UV light from the sun is __% UVB and __ % UVA

A

5, 95

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9
Q

Photoaging is caused by:

A

UVA (penetrates deeper)

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10
Q

Which UV gives you wrinkles?

A

UVA

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11
Q

Which UV spectrum penetrates the skin deepest?

A

UVA

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12
Q

What are some modifiers of UVR?

A

Altitude (4% with 1000 ft)
Surface reflection (water<snow)
Cloud cover only scatters

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13
Q

What is the deepest layer that C, B, and A get to

A

C gets to top of epidermis
B gets to top of dermis
A gets deep into dermis (vessels)

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14
Q

What is an action spectrum?

A

determined by UV absorbing properties of molecule that initiates the response: chromophore

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15
Q

What are some major UVB chromophores?

A

DNA, urocanic acid, aromatic AAs

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16
Q

Which wavelength is used to treat psoriasis?

A

310 nm

17
Q

Which spectrum is most responsible for photodamage / effects of UV on skin?

A

UVB

18
Q

What are some acute effects of UVR on skin?

A 
Inflammation/sunburn
Immunomodulation
Tanning (A immediate)
Epidermal hyperplasia
Vit D synthesis
DNA damage/apoptosis
19
Q

Explain erythema, heat, swelling, and pain of sunburn

A

Erythema: vasodilation
Heat: inc blood flow
Swelling: vasoperm inc
Pain: cytokine release

20
Q

Sunburn cells are what type and look like what

A

keratinocytes, purple blobs with fuzzy red halos

21
Q

Immediate tanning is caused by:

A

UVA and visible light cause oxidation and melanin redistribution (NOT production)

Not proective like a UVB tan

22
Q

Delayed tanning is caused by

A

UVB, 3 days or so later, inc melanin and inc transfer of melanosomes to keratinocytes

Photoprotective

23
Q

What is solar elastosis?

A

Accumulation of abnormal elastin in the skin as a result of photodamage

24
Q

What are some features of photoaging?

A 
Inelastic
Telangiectasia
Irregular pigmentation: ephelides/freckles, solar lentigo/age spot, hypo pigmentation
Comedones and cysts
Actinic keratosis and malignancy
Benign growths
25
Q

Favre-Racouchot syndrome is?

A

skin disease in sun damaged individuals characterized by yellowish thickening of skin with nodules, comedones and follicular cysts

WITCH FACE

26
Q

Compare UVB and UVA radiation damage

A

UVB is 20-50x more potent, but UVA is higher in quantity and penetrates deeper

27
Q

Which UV causes most DNA damage and how so?

A

UVB, through direct absorption (chromophore) and exposure to nearby chromophores

28
Q

What happens to DNA upon UV exposure?

A

covalent dimers of adjacent pyrimidines, either as cyclobutane dimers or 6,4 products (UVB specifically for 6,4)

29
Q

What are some signature UV mutations?

A

C->T

CC-> TT

30
Q

What mechanisms protect against UVR and what layer are they in?

A 
Stratum corneum: reflection
Melanin - absorption
Tumor suppressors - p53, PTCH, CDKN2A
DNA repair
Apoptosis
31
Q

What is the defect in xeroderma pigmentosum?

A

Usually defects in nucleotide excision repair

AR

32
Q

What three areas are involved in XP?

A

Skin, eyes, CNS

33
Q

What are the most common causes of death in XP?

A

Metastatic skin cancer and neurologic degeneration

34
Q

What cells are particularly vulnerable to DNA damage?

A

Lymphocytes and Langerhans - immunosuppression

Langerhans disappear

35
Q

Describe why tanning bads are bad emk?

A

UVA mostly, 5x normal
10x less protective
strong assoc w melanoma and non-mel skin cancer

OS Derm (20 decks)

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