What causes itching?

[biggestmexi]

Doctor,

Why do you itch? What causes the sensation if nothing touches you?

[Dr Steve]

Originally Posted by biggestmexi

Doctor,

Why do you itch? What causes the sensation if nothing touches you?

Great question!

Itching (called "pruritus" in medical terms...I know I know we have a different word for everything) is caused by the actuation of tiny nerve endings in the skin. Itch sensation is sent to the brain through a network of nerve cells called "C" fibers...not that important to the discussion at hand, but just know that there is a special pathway in the nervous system for the sensation we call "itching."

Lots of things can cause itching. When it happens for "no reason", it's usually a release of histamine in the skin due to some minor exposure that you aren't even aware of. Or sometimes the histamine containing cells just blow up for no reason, causing localized itching. Irritants, drugs (especially narcotics), allergic reactions, and bug venom all can cause itching.

A generalized release of another chemical, called bradykinin, causing swelling, itching, and trouble breathing is called angioedema, and is a badass thing to have happen to you. Here's what it looks like:

[biggestmexi]

so what the purpose of having this dedicated system? is there really a reason for itching?

other than some animals and plants defenses (i.e poison fucking ivy)

[Rube]

Originally Posted by Dr Steve

That's what Uncle Tommy's lips look like.

[MC Pee Pants]

You should read A Natural History of the Senses by Diane Ackerman. Its really interesting and explains a lot of this kind of stuff and makes you appreciate itching.

[boosterp]

Man, this takes me back to a paper I did for a physiology class. The devil that is itching.