You Asked ...WE ANSWERED! EXPERTS REVEAL THE SHOCKING TRUTH BEHIND THE MYSTERIES OF SCIENCE. What's an itch and why does it go away after you scratch it? Jennifer Kaufman, 14 Mobile, Ala. Here's an answer that may make you scratch your head. "The best definition science can come up with for itching [or pruritus pruritus /pru·ri·tus/ (proo-ri´tus) itching.prurit´ic pruritus a´ni intense chronic itching in the anal region. pruritus hiema´lis xerotic eczema. ] is a sensation that makes you want to scratch," says Stephen Webster, a dermatologist (skin expert) at Gunderson Lutheran Medical Center in LaCrosse, Wisconsin. "We still don't know everything about what makes you itch." Some scientists think you can get itchy just thinking about it. An itch usually occurs when skin becomes irritated. Common skin irritants: mosquito bites, bee stings, poison ivy, and other allergens--compounds that cause allergic reactions, which range from strawberries to chocolate to pets. Allergens can trigger the body's release of an excessive amount of chemicals including histamine, that dilates or expands blood vessels. This lets more blood flow to the irritated area, Webster explains, and produces bumpy red rashes or hives hives (urticaria), rash consisting of blotches or localized swellings (wheals) of the skin, caused by an allergic reaction (see allergy). The swelling is caused by distention of the skin capillaries and escape of serum and white cells into the skin and tissues. , forms of skin inflamation called dermatitis. Skin damage like dry skin and sunburn sunburn, inflammation of the skin caused by actinic rays from the sun or artificial sources. Moderate exposure to ultraviolet radiation is followed by a red blush, but severe exposure may result in blisters, pain, and constitutional symptoms. can also induce an itch. Then, scientists think, nerve fibers called cutaneous cutaneous /cu·ta·ne·ous/ (ku-ta´ne-us) pertaining to the skin. cu·ta·ne·ous adj. Of, relating to, or affecting the skin. Cutaneous Pertaining to the skin. sensory neurons signal the brain with a "SCRATCH ME HERE." A scratch may relieve a minor itch like a bug bite, because scratching disperses (spreads out) histamines, Webster explains. This temporarily slows histamines from interacting with the affected spot. But in more severe cases of dermatitis, a scratch can inflame an irritation and make you itch more. "It's like hitting a broken leg with a hammer," says Webster. "You don't give your skin a proper chance to heal." A cold compress or rinsing irritated skin in cool water may be the oldest way to ease an itch. Common ingredients like camphor camphor (kăm`fər), C10H16O, white, crystalline solid ketone with a characteristic pungent odor and taste. It melts at 176°C; and boils at 204°C;. or menthol menthol, white crystalline substance with a characteristic pungent odor. It is derived from the oil of the peppermint plant, Mentha piperita (see mint), or prepared synthetically from coal tar. in over-the-counter ointments can numb sensory nerve endings and mask an itch with a tingling sensation. For more severe irritations, oral antihistamines Antihistamines Definition Antihistamines are drugs that block the action of histamine (a compound released in allergic inflammatory reactions) at the H1 can prevent the release of histamines. While it's tempting to scratch an extremely painful case of dermatitis, for a speedy recovery, try to remember: HANDS OFF! HAVE A SCIENCE QUESTION? Send it to: You Asked! Science World 555 Broadway New York, NY 10012 Include your name, age, school name, address, and phone number. |
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