human bio 11. *ultraviolet radiation has three different wave lengths – uv-a, uv-b, and uv-c....
DESCRIPTION
Ultraviolet Spectrum UVC UVBUVA X rays VisibleTRANSCRIPT
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Human Bio 11
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* Ultraviolet radiation has three different wave lengths – UV-A, UV-B, and UV-C.
UV-A starts the tanning process before the skin burns and has the least cancer risk.
UV-B the tan is darker and longer lasting but tends to produce burns before it tans. It is a known cancer risk.
UV-C has most energy but the least penetrating. Dead layers of skin stop UV-C radiation, but it is dangerous to living cells having carcinogenic effects.
The sun produces rays….
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Ultraviolet Spectrum
100-280 280-210 310-400
UVC UVB UVAX rays Visible
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Skin Cancer
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Skin Cancer
• The major factor in skin cancer formation is sun exposure
• Skin type is also important in dictating how the skin reacts to the sun
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Basal Cell Carcinomas
• Commonest skin cancer in Caucasian populations
• Major cause is sun exposure• Common sites on face and trunk• Not metastatic
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Squamous cell carcinoma• Second most common skin cancer in Caucasian
populations• Caused by sun exposure - chronic sun exposure• Most at risk are those with pale skin who burn in
the sun• Commonest on sun exposed areas• Pre-cancerous lesion is the solar keratosis• Metastatic potential - to regional lymph nodes,
then liver, lungs etc
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Melanoma
• Third most common skin cancer• Caused by severe intermittent bouts of sun
exposure• Found on sun exposed and non-exposed sites• Second most common cancer to affect young
women• High metastatic potential - local, lymph nodes,
lung, liver and brain
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Melanoma
• 30% arise in a pre-existing mole– Features to look out for are asymmetry of the
mole, irregular shape and irregular colour
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How can we prevent long term skin damage?
• Avoid sun• Avoid midday sun• Use photo-protective
clothing, hats etc• Use sunblocks
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SandSEA
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How sunscreen works
• Work either by reflecting or absorbing UV rays
• Most sunscreens protect us from UV-A and UV-B.
• Ingredients like zinc oxide or titanium oxide reflect or scatter ultraviolet (UV) radiation.
• Octyl methoxycinnamate (OMC) or oxybenzone absorb UV radiation, dissipating it as heat.
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Sun Protection Factor
• Indication of the amount of time it is safe to spend in the sun without burning
• Ex: an SPF of 10 would allow an exposure ten times greater than normal