Goose bumps

This article is about the bumps that form on skin. For the book series by R. L. Stine, see Goosebumps.

Image:Goose bumps.jpg Goose bumps (AE), also called goose pimples, goose flesh (BE), chicken skin (Hawaiian Pidgin), or cutis anserina, are the bumps on a person's skinat the base of body hairswhich involuntarily develop when a person is cold or experiences strong emotions like fear. The reflexof producing goose pimples is known as horripilation, piloerection, or the pilomotor reflex. It occurs not only in humans but also in many other mammals; a prominent example are porcupineswhich raise their quills when threatened.

Goose bumps are created when tiny musclesat the base of each hair, known as arrectores pilorum, contract and pull the hair erect. The reflex is started by the sympathetic nervous system, which is in general responsible for many fight-or-flight responses.

Goose bumps are often a response to cold: in animals covered with furor hair, the erect hairs trap air to create a layer of insulation. Goose bumps can also be a response to fear: the erect hairs make the animal appear larger, in order to intimidate enemies. This can for example be observed in frightened cats. In humans, it can even extend to piloerection as a reaction to hearing nails scratch on a chalkboard.

Piloerection as a response to cold or fear is vestigialin humans; as humans retain only very little body hair, the reflex now serves no known purpose.

In humans, goose bumps are strongest on the forearms, but also occur on the legs, back, and other areas of the skin that have hair. In some people, they even occur in the face or on the head.

Piloerection is also a (rare) symptomof some diseases, such as temporal lobe epilepsy, some brain tumors, and autonomic hyperreflexia. A skin condition that mimics goose bumps in appearance is keratosis pilaris.

Goose bumps can only occur in mammals, since other animals do not have hair. The term "goose bumps" is therefore misleading: the bumps on the skin of a plucked goosetechnically do not qualify as piloerection. Birds do however have a similar reflex of raising their feathers in order to keep warm.

The Latinhorrere is the root of words such as "horrific" or "horror"; it means "to stand on end" and refers to the standing hairs of goose bumps.

References

• US National Library of Medicine explanation of goosebumps

• Medical terms explanation of piloerection the technical term for goosebumpsde:Gänsehaut

nl:Kippenvel

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It uses material from the http://en.wikipedia.org/wiki/Goose+bumps Wikipedia article Goose bumps.