Fitz9. Ch17: Cutaneous Photobiology

Question 1

What are the wavelengths for
UVB?
UVA2?
UBA1?

Answer 1

UVB: 290-315

UVA2: 315-340
UVA1:340-400

Question 2

Energy from an excited chromosphere is transferred to another molecule

Answer 2

Photosensitized reaction

Question 3

Photo emission from return of triplet excited states to ground state, which have longer wavelengths than fluorescence

Answer 3

Phosphorescence

Question 5

Most effective wavelength to facilitate photosynthesis of cutaneous vitamin D

Answer 5

UVB 297 nm

Question 6

UV induced erythema peaks at

Answer 6

300 nm

Question 7

Acute photo sensitivity with a decreased UVB minimal erythema dose is seen in what disease?

Answer 7

Xeroderma pigmentosum

Question 8

Histologic difference between sunburn and tanning?

Answer 8

Sunburn: epidermal edema with spongiosis and few apoptotic keratinocytes while

Tanning: increase in basal and suprabasal melanin in the epidermis

Question 9

Psoriasis

Answer 9

NB UVB 311 to 313 nn

Question 10

Most important premutagenic DNA lesions

Answer 10

Pyramid one dimers

Question 11

UV mutator phenotype

Answer 11

Loss of p53

Question 12

Central regulators of apoptosis

Answer 12

Caspases

Question 14

UVA vs UVB

UVB is…

Answer 14

UVB is
1000 times more erythemogenic and associated with sunburn,
Delayed melanogenesis in days, 
MAJOR role in carcinogenesis, 
Less role in photoaging, 
Penetrates in upper Derm is only,
Role in Vitamin D production
Does not penetrate window glass
Also immunosuppression