Ultraviolet Radiation and the Ozone Layer – Flashcards
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Job of the ozone layer
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filter damaging UV rays that cause health problems - skin, eyes, immune system
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Children born today have what chance of developing skin cancer?
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1/7
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About __% of skin cancer cases are melanoma skin cancer (lethal)
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10%
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_____ cancer is the most common form of human cancer.
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Skin
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It has also been estimated that how many Americans who live to age 65 will develop skin cancer at least once?
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nearly half
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What is the most common warning sign of skin cancer?
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change in the appearance of the skin, such as a new growth or a sore that will not heal.
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The term "skin cancer" refers to three different conditions. They are?
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1. basal cell carcinoma 2. squamous cell carcinoma 3. melanoma
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Two most common forms of skin cancer are
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basal cell carcinoma and squamous cell carcinoma.
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Basal cell carcinoma and squamous cell carcinoma are referred to as what?
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nonmelanoma skin cancer.
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______is generally the most serious form of skin cancer because it tends to spread (metastasize) throughout the body quickly.
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Melanoma
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Skin cancer is also known as _________.
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skin neoplasia
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most common of all cancers
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basal cell carcinoma
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Important factors in developing basal cell carcinoma are what?
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Light-colored skin, sun exposure, and age. People who have fair skin and are older have higher rates of basal cell carcinoma.
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The ___ remains the most common location for basal cell lesions.
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face
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Basal Cell Carcinoma arise from where?
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These cancers arise in the basal cells, which are at the bottom of the epidermis
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Cause of Basal Cell Carcinoma
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Chronic exposure to sunlight BCC occur most frequently on exposed parts of the body (face, ears, neck, scalp, shoulders, and back)
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Pathophysiology of Basal Cell Carcinoma
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UV-induced mutations in the TP53 tumor suppressor gene, which resides on chromosome 17p of pluripotential cells within the basal layer of the epidermis. These pluripotential cells (a stem cell that has the potential to differentiate into any of the three germ layers ) are capable of forming hair, sebaceous glands (secretes sebum), and apocrine glands (sweat glands)
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Tumors are most often discovered on hair-bearing areas in what type of skin cancer
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Basal Cell Carcinoma
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Second most common form of skin cancer
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squamous cell carcinoma
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Squamous cell carcinoma
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Squamous cell carcinoma is cancer that begins in the squamous cells, which are thin, flat cells that look like fish scales under the microscope
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Squamous cells
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Squamous cells are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts. Thus, squamous cell carcinomas can actually arise in any of these tissues.
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Squamous cell carcinoma of the skin occurs roughly ______ as often as basal cell carcinoma.
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1/4
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__________ and a _________ are even more important in predisposing to this kind of cancer than to basal cell carcinoma
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Light coloured skin and history of sun exposure.
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The earliest form of squamous cell carcinoma is called ___________.
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actinic (or solar) keratosis. Actinic keratoses appear as rough, red bumps on the scalp, face, ears, and backs of the hands. They often appear against a background of mottled, sun-damaged skin. They can be quite sore and tender, out of proportion to their appearance
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The single most important factor in producing squamous cell carcinomas is ____________.
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sun exposure
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SCC is most likely to occur in areas where?
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the skin has suffered certain kinds of injury (burns, scars, long-standing sores)or sites previously exposed to X-rays or certain chemicals (such as arsenic and petroleum by-products)
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In addition, chronic skin inflammation or medical conditions that suppress the immune system over an extended period of time may encourage the development of _________.
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Squamous cell carcinoma
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Basal and squamous carcinoma cell latency
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A long latency period of 20-50 years is typical between the time of UV damage and clinical onset of BCC. 1) aging population 2) cumulative UV exposure
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Melanocytes
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Cells present in the epidermis. These skin cells make the protective brown pigment called melanin.
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________ is what makes the skin tan or brown. It is formed to protect the deeper layers of the skin from the harmful effects of the sun
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Melanin
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Melanoma pathophysiology
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Melanoma is a malignant tumor (uncontrolled growth of pigment cells) that originates in melanocytes, cells which produce the pigment melanin that colors our skin, hair, and eyes
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____________ accounts for 75 percent of all deaths associated with skin cancer
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malignant melanoma
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An individual's risk for developing melanoma depends on two groups of factors: intrinsic and environmental - give examples of each.
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Intrinsic factors are generally an individual's family history and inherited genotype The most relevant environmental factor is sun exposure.
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Epidemiologic studies suggest that exposure to ___________ is one of the major contributors to the development of melanoma.
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Ultraviolet Radiation UVA & UVB
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UV radiation causes damage to the_____, which when unrepaired can create _______in the cell's genes.
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DNA of cells , mutations
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Melanoma & spreading
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Once the cancer advances and metastasizes (spreads) to other parts of the body, it is hard to treat and can lead to death
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During the past 10 years the number of cases of _______ has increased more rapidly than that of any other cancer
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melanoma
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Non melanoma are ______ more common than melanoma
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10x
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ABCDE s of Melanoma skin cancer
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asymmetry, boarder, color, diameter, elevation
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Skin erythema
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Sunburn: Solar erythema is associated with microscopic changes in the skin, detectable within 30 minutes of exposure to UV. The most characteristic change include the formation of epidermal sunburn cells and the swelling of superficial blood vessels (redness of the skin)
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When does sun burn happen?
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Sunburn results when the amount of exposure to the sun or other ultraviolet light source exceeds the ability of the body's protective pigment (melanin) to protect the skin
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A serious sunburn is as serious as a thermal burn, and may have the same systemic effects such as..?
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blistering, edema (abnormal accumulation of fluid beneath the skin) and fever
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Sunburn and melanin (pigment)
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Compared with white-skinned individuals, moderately pigmented skin require 3-5 times more UV exposure to cause erythema Darker-skinned individuals require up to 30 times more UV exposure. Facultative (induced) tanning increases MEDs (minimal erythema dose) by only 2-3 times.
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How does tanning happen?
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1) immediate pigment darkening, which occurs during exposure, results from alteration of existing melanin (oxidation, redistribution) 2) delayed tanning results from increased synthesis of epidermal melanin and requires a longer period of time to become visible
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Up to ___% of cataracts are due to UV exposure to the eye
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20%
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What is Cataracts?
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A cataract is the clouding of the normally clear lens of the eye
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Other causes of cataracts
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Diseases (diabetes) Smoking + alcohol Some prescription drugs
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Photokerititis (snow blindness)
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Exposure to UV radiation from the sun can Also lead to a "sunburn" of the cornea (clear surface of the eye)This occurs when proper precautions are not used at high altitudes, where a greater amount of unfiltered (by the atmosphere) UV is present. The exposure may be compounded by reflection from the snow. Snow reflects 85% of UV-B
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The intensity of UV energy increases by 5% for every ____ increase in altitude above sea level
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300m
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Snow blindness & symptoms
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High exposure to UV-B can cause a corneal burn within one hour, although symptoms may not become apparent for six to 12 hours. Symptoms include excessive tearing, pain, redness, swollen eyelids, pain when looking at light, headache, a gritty sensation in the eyes, and decreased (hazy) vision
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Treatment for snow blindness
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patching the eye closed after instilling a few drops of ophthalmic antibiotic solution, because the surface of the cornea will regenerate spontaneously in 24 to 48 hours
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Pterygium
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Pterygia are wing-shaped growths of benign fibrous tissue with blood vessels typically located on the surface of the sclera. In extreme cases, pterygia may grow onto the eye's cornea and interfere with vision. These growths on the eye's surface can become unsightly and cause corneal problems as well as distorted vision
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________ are thought to help cause pterygia.
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UVB rays
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it is believed that the decreased immune responses observed after UV irradiation serve to prevent what?
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excessive inflammation and damage to the skin that has been exposed to the sun
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Relatively low doses of UV-B compromise the ____________ of the skin, thus limiting the skin's allergic response to local attacks
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immunological defences
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Higher doses of UV-B can lower an individual's overall ______________.
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immunological response
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Suns damages to the immune system
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increased risk of the incidence and severity of infectious disease increased risk of malignant melanoma diminished efficacy of vaccinations
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Is a tan healthy?
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A suntan is not a sign of health - it shows that your skin has been damaged. Sun damage is not reversible and usually happens before you can see or feel it.
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Does a tan protect you from sun damage?
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Overexposure to the sun increases your risk of skin cancer and causes premature wrinkling.
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Are people with dark skin protected?
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Everyone, regardless of skin type, needs protection from the sun.
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Does shade prevent burning?
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Even if it's cloudy, surfaces such as water, sand, concrete, and snow reflect the sun's rays on to your skin. Clouds filter about 80 percent of the ultraviolet rays, but UV can penetrate thin clouds, fog and haze.
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Can you sunburn when swimming?
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The sun's rays penetrate under water. Radiation penetrates deeper into the skin when it is wet. Wear a t-shirt and hat while in the water. Use a water resistant sunscreen and re-apply it frequently and liberally.
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Can glass protect you from UV rays?
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UVA rays can penetrate glass and produce some tanning, both immediate and delayed. This can cause premature aging and skin cancer.
