On Tuesday 07 Apr 2009 12:25:19 pm Kiran K Karthikeyan wrote: > http://news.bbc.co.uk/2/hi/health/7976606.stm > > *Scientists have shown scratching helps relieve an itch as it blocks > activity in some spinal cord nerve cells that transmit the sensation to the > brain.* > > However, the effect only seems to occur during itchiness itself - > scratching at other times makes no difference. > > While it is widely-known scratching relieves an itch, the physiological > mechanisms for how this works are little understood.
I am no neuroendocrine expert on itching but over the years I have developed theories which have no proof and I read idly when something related appears. One of the first things I was taught in physiology as a medical student was the ppearance of a red line on the skin called a "weal" when said skin is scratched with a blunt object. The weal appears because chemicals are released under the skin that cause blood vessels to dilate up and leak fluid in response to injury. Scratching achieves exactly this efect and I am surprised if there is no link between the release of local chemicals in respnse to a sctratch that help mask the itch. Shyam - are you reading? You might know. The other thing is the psychological appearance of an itch. If you are walking along a road and you stare at a good looking woman long enogh she will eventually develop a itch on her forehead that will cause her to raise her hand and scratch that itch. Funnily enough the raising of the hand also shields her face and possibly her upper chest as well from your stare. But if she is asked, she will admit only to an itch. Maybe science will either corroborate or rubbish my observations one day.... But I must point out that even my dog has a psychologically provoked itch. She scratches when she is upset at not being allowed to do something. shiv
