UV Radiation and Skin Flashcards
___ radiation is outside the visible light spectrum. ___ wavelength means more energy and more ability to displace ___.
UV
Shorter
Electrons
Most important UB radiation types are ___ and ___
UVA
UVB
When UV light hits the skin, it can be ___, ___, or ___.
Good radiation absorbers are ___ amino acids, ___ ___, and polymers like ___.
Absorbed
Transmitted
Scattered
Aromatic
Nucleic acids
Melanin
UVA has a longer wavelength and therefore scatters ___, and travels ___ into the skin
Less
Deeper
Damage only occurs when radiation is ____.
Absorbed
Tyrosine is ___ and that’s why it’s part of melanin synthesis.
Aromatic
Scale of skin types: Fitzpatrick scale:
Sunburn is caused by covalent linking of ____. Kink in the DNA. Phospholipids of the cell membrane produce ___ ___ metabolites leading to dilation of blood vessels, Degranulation of mast cells, and release of cytokines
Pyrimidine
Arachidonic acids
1 week after sun burn, ___ of the skin. Melanin actually gets darker. Keratinocytes secrete factors that stimulate melanocytes to produce more melanin
Darkening
High UV doses causes blistering and skin ___.
Desquamation
Risk of melanoma increased by ___ when tanning bed use is before age 35.
75%
Review factors that affect UV dose:
UV exposure in the dermis:
causes down regulation of ___, up regulation of _____ produced by dermal fibroblasts, less ___ and more disorganized masses of elastic fibers, melanin is not as effective in protecting the dermis.
Collagen
Metalloproteinases
Elastin
___ __ is disorganized masses of elastic fibers
Solar elastosis
Why sunscreen?
The nucleotide excision repair system is not perfect. If there is too much damage there is too much to repair. If the Pyrimidine dimer is in a sequence that encodes a tumor suppressor gene…. Like p53…. More harmful
UVA is more the culprit for ____ (solar elastosis). UVB is more risk for ____. and riskier for ___.
Dermatoheliosis
Sunburn
Cancer
False
SPF stands for ___ ___ ___, measures how much UV radiation is required to produce sunburn on protected skin versus the amount of UV radiation required to produce sunburn on unprotected skin. Wearing SPF 30, means it would time 30 times more UV radiation to produce a sunburn
Sun Protection Factor
Recommended everyone wear SPF __ and apply every __ hours.
30
2
____ ___ sunscreen must protect against UVA and UVB
Broad spectrum
Types of sunscreen:
_____ (mineral or inorganic): block or scatter UV using titanium dioxide or zinc oxide
_____ (organic): absorb the UV light and re-emit the energy as heat
Physical
Chemical
Positive of UV radiation:
Vitamin D metabolism. We can get it from the ___ but generally not enough. _____ is photochemically transformed in the skin by UVB radiation into pre-vitamin D3 which is isomerized to vitamin D3. Liver and kidneys help.
7-dehydrocholesterol
UV effect on immune system:
Keratinocytes have the ability to activate ___ immune responses. Langerhan’s cells bridge the adaptive and innate
Innate
After UV exposure, ___ langerhans cells in epidermis, langerhans cells that are ___ in antigen presentation at the spleen, ___ generation of suppressor T lymphocytes thought to be mediated by IL-10 and TNF-alpha.
Decreased ___ immunity and decreased ability to activate ___ immune response
Decreased
Defective
Increased
Local
Adaptive
UV allowing carcinogenesis by effecting the immune system:
Immunosuppressive medication long term use can result in higher rates of ___ __ __ and __ __ ___.
Basal cell carcinoma
Squamous cell carcinoma
Harnessing the immune suppression from UV light:
Lupus sometimes improves with UV light with the right ___.
Wavelength
