UV Light Lecture Flashcards
UVC Spectrum
200-290 Most potent but does not penetrate the atmosphere. When made it will kill epidermal cells
UVB Spectrum
290-320 The SUNBURN spectrum- SPF is based on this wavelength
UVA Spectrum
320-400nm Least potent but penetrates the deepest. Associated with SKIN CANCER and photo-aging
What increases UV exposure ?
Closer to the equator, Higher altitude, Higher reflective index ( Water-7%, Sand-25%, Snow-80%)
What affect do clouds have on UV ?
They scatter but do not absorb
What is the action spectrum of UV light ?
Different spectrums of light cause different diseases. The wavelength of the certain reaction is the action spectrum
What property of the UV light damages the skin ?
The chromophore of the light
What are the major UVB Chromophores ?
DNA, Urocanic Acid, Aromatic Amino Acids
What is the optimal wavelength for psorias treatment and Burning
295nm
What determines susceptibility to burning ?
Skin Phototype
What causes the symptoms of sunburn ?
Due to UVB
- Erythemia from vasodilation
- Heat from Inc. Blood flow
- Swelling from vaso-permibility
- Pain from cytokines
What are sunburn cells ?
They are cells damaged by UVB, they show inflammation, edema (Intracell and perivascular) perkeritosis and acanthosis
What casuses the immediate tanning response
UVA- Begins with radiation and fades within an hour. Does not protect against UVB.
**Oxidation and redistribution of melanin
What causes the delayed tanning response ?
UVB- visible after 72 hours and lasts for weeks. Caused by increased melanin synthesis.
What are solar elastoses ?
Clumps of melanin
What are some effects of chronic sun exposure ?
Telangiectasia, Pigment abnormalities, Solar elastoses, Solar letigines Cyst and comedone formation
What are the malignant changes in DNA from the sun ?
Cyclobutane dimers and 6,4 photoproducts
How does the body protect from these mutations ?
Stratum corneum- reflection Melanin- absorption Tumor Supressor genes DNA repair pathways Apoptosis
What causes Xeroderma Pigmentosum
A defect in nucleotide excision repair
What are the immune effects of sun exposure ?
Lymphocytes and Langerhans cells are damaged
Tanning beds —->
Emit UVA… This is the cancer spectrum. Does not protect against UVB which is what gives you a sunburn.
How intense are tanning beds ?
They emit > 5x the amount of UVA than a unit of time in the sunlight.
