Sunburn is Damage to the epidermis and sometimes the dermis, the top and middle layers of the SKIN, as a consequence of extended, unprotected sun exposure. The sun emits several wavelengths of ultraviolet light. Those that reach the earth’s surface are ultraviolet A (UVA) and ultraviolet B (UVB). Each affects the skin in different ways. UVA activates melanocytes, the cells that produce melanin (pigment) and may produce a thermal (heat) response that causes the skin to turn red. Though the skin may feel hot, this is not actually sunburn but rather a thermal (heat) response.
Sunburn is a delayed response to UVB exposure. UVB lightwaves do not activate the melanocytes but instead affect keratinocytes. When the epidermis (skin’s outer layer) contains deeply pigmented keratinocytes, such as in a person who has dark skin or a tan from previous sun exposure, the pigment (melanin) absorbs the UVB and the keratinocytes escape damage. When the skin is light, melanin distribution is also light and there is little absorption of UVB.
The keratinocytes bear the brunt of the exposure, and about 8 to 12 hours later show the consequences. The damaged cells release toxins and other substances that draw increased BLOOD flow to the dermis. The additional blood flow causes the skin to become red (erythema). These toxins irritate the nerve endings in the epidermis and dermis, causing PAIN. Fluid may accumulate between the cells (edema), causing swelling. With more severe damage, fluid-filled blisters form on the skin. Discomfort peaks about 48 hours after exposure. At about this same time, the melanocytes have infused keratinocytes migrating from the dermis to the epidermis with melanin, giving them a darker pigment that will offer better protection than their predecessors had.
The most effective treatment for sunburn is a combination of moisturizing lotion or gel such as aloe vera to soothe the irritated skin and a nonsteroidal anti-inflammatory drug (NSAID) such as ibuprofen to relieve INFLAMMATION and pain. Most sunburn discomfort resolves in three to five days. Badly sunburned skin that has blistered is likely to peel at this point and requires gentle cleansing to minimize the risk for bacterial INFECTION until the new skin completely heals. Researchers now believe one significant sunburn is sufficient to lay the groundwork for skin cancer decades later. Repeated mild to moderate sunburns appear to have similar effect. Sunscreens and protective clothing worn during sun exposure can protect against sunburn.
Resource: Facts On File Encyclopedia Of Health And Medicine
Xanthoma is a fatty deposit that forms a benign (noncancerous) LESION beneath the SKIN, though also may occur in other tissues. Xanthomas develop in people who have chronic, untreated HYPERLIPIDEMIA (elevated BLOOD cholesterol and triglycerides levels). In their most common form, xanthomas appear as yellowish blebs beneath the skin, typically rounded or
Wrinkles are furrows or channels in the SKIN, typically resulting from repeated movements, such as facial expressions (for example, crow’s feet and laugh lines), or from long-term exposure to sun and wind. Aging is the single-most significant factor that causes wrinkles. Wrinkles increase with age as the skin loses collagen and subsequently
Whitlow is an INFECTION at the end of the finger, or less commonly the end of a toe, that contains pus and is very painful. The area is inflamed, enlarged, erythematous (reddened), and often oozing. A common cause of whitlow is infection with the HERPES SIMPLEX VIRUS (HSV), conveyed to the finger via contact with infectious secretions from oral herpes
Wheal is a raised, blisterlike LESION on the SKIN that usually results from an intradermal injection such as for ALLERGY skin testing or the tuberculin skin test. Wheals also may occur in response to insect stings and topical allergic reactions (URTICARIA or hives). Wheals associated with urticaria typically itch, sometimes intensely. Wheals usually do not
What are Warts and What Causes Warts Wart is a growth, typically rough and raised, that appears on the SKIN. The HUMAN PAPILLOMAVIRUS (HPV), which has numerous strains, causes common warts as well as variations including genital warts (a common sexually transmitted disease) and plantar warts which appear on the soles (plantar surfaces) of the feet. Because
Vitiligo - a condition of hypopigmentation in which melanocytes die in patches of SKIN, leaving macules that are pale and depigmented. Dermatologists believe vitiligo is an autoimmune disorder in which the IMMUNE SYSTEM produces antibodies that attack melanocytes, the skin cells responsible for producing pigment. Vitiligo affects people of all races and
Vesicle is a small, blisterlike LESION on the SKIN that contains serous fluid. Vesicles typically occur in clusters and indicate INFECTION, such as with HERPES SIMPLEX VIRUS (HSV), or irritation, such as results from contact with poison ivy. Skin vesicles often hurt or itch. Treatment may include topical medications to relieve discomfort, with oral
What is Urticaria and Definition Urticaria is the clinical term for hives, an outbreak of wheals on the SKIN’s surface. Acute urticaria, which comes on suddenly, typically signals a HYPERSENSITIVITY REACTION. The wheals contain fluid the IMMUNE RESPONSE draws from the cells of the skin. They itch, often intensely (PRURITUS), and may appear and recede
Toxic Epidermal Necrolysis is a life-threatening inflammatory condition affecting the SKIN and underlying connective tissues, also called Stevens-Johnson syndrome. Toxic epidermal necrolysis usually results as an adverse DRUG reaction though may occur as a complication of INFECTION or CANCER. Doctors believe toxic epidermal necrolysis develops when an
What is Tissue Expansion Tissue Expansion is a method for growing additional SKIN to use for autologous (self) skin grafts. Autologous grafts have the best rate of success when transplanted because they are native to the body and present no risk for graft rejection. Tissue expansion is a common method for many reconstructive surgery procedures, though