1.6 ULTRAVIOLET LIGHT Flashcards
Electromagnetic spectrum
Ultraviolet light (UV) is made up of
- Vacuum UVC (10–200 nm)
- UVC (200–280 nm)
- UVB (280–320 nm)
- UVA (320–400 nm)
UVA (320–400 nm) is divided into?
UVAII (320–340 nm)
and
UVAI (340–400 nm)
Solar radiation is made up of ?
~50% visible light
40% infrared
9% UVR
At what time of the day is UVA radiation present vs UVB?
UVA is present consistently from sunrise to sunset
vs
UVB peaks around noon
UVA , UVB daytime diagram
Light has properties of both waves and photons
What element of the skin is necessary for light in order to be absorbed and have a cutaneous effect?
Chromophores
either of the epidermis or dermis
Name all the possibile chromophores present in the epidermis
nucleic acid
protein
urocanic acid
melanin
Name the chromophores of the dermis
Hemoglobin
Porphyrins
Define absorption spectrum
the portion of the electromagnetic (EM) spectrum that is absorbed by a particular molecule or chromophore
Define action spectrum
the portion of the EM spectrum that produces a particular effect
Which part of UV radiation is responsible for converting provitamin D3 (7-dehydrocholesterol) to previtamin D3?
UVB (280–320 nm)
What percentage of total vitamin D stores is produced via skin vs dietary intake?
90% skin
vs
10% dietary intake
Type of vitamin clinically D measured to assess vit D stores
vs
type of actually active vitamin D?
25-hydroxyvitamin D3
vs
1,25-hydroxyvitamin D3
Define minimal erythema dose(MED)
minimal amount of a particular UVR that leads to minimal erythema of the exposed skin
MED
