goose bumps

Goose bumps on a person

Goose bumps, also called goose flesh, goose pimples, chill bumps, or the medical term cutis anserina, are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is cold or experiences strong emotions such as fear or awe. The reflex of producing goose bumps 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 porcupines which raise their quills when threatened, or sea otters when they encounter sharks or other predators.

Anatomy and biology

Goose bumps are created when tiny muscles at 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.

As a response to cold: in animals covered with fur or hair, the erect hairs trap air to create a layer of insulation. Goose bumps can also be a response to anger or fear: the erect hairs make the animal appear larger, in order to intimidate enemies. This can be observed in the intimidation displays of chimpanzees,^[1] in stressed mice^[2] and rats, and in frightened cats. In humans, it can even extend to piloerection as a reaction to hearing nails scratch on a chalkboard, listening to awe-inspiring music,^[3] feeling or remembering strong and positive emotions (e.g., after winning a sports event),^[4] or to an intellectual or spiritual epiphany.

Piloerection as a response to cold or emotion is vestigial in humans; as humans retain only very little body hair, the reflex (in humans) now provides no known benefit.

In humans, goose bumps are strongest on the forearms, but also occur on the legs, neck, and other areas of the skin that have hair. In some people, they even occur in the face or on the head. In humans, the areolas of the breasts of females typically show piloerection because of hormonal distribution, for example, when aroused or inside the maternity cycle.

Piloerection is also a (rare) symptom of some diseases, such as temporal lobe epilepsy, some brain tumors, and autonomic hyperreflexia. Goose bumps can also be caused by withdrawal from opiates such as heroin. A skin condition that mimics goose bumps in appearance is keratosis pilaris

References

1. ^ Martin Muller and John Mitan. Conflict and Cooperation in Wild Chimpanzees. Advances in the Study of Behavior, vol. 35
2. ^ Masuda et al. Developmental and pharmacological features of mouse emotional piloerection. Experimental Animals, 1999 Jul;48(3):209-11. PMID 10480027
3. ^ David Huron. Biological Templates for Musical Experience: From Fear to Pleasure. Abstract
4. ^ George A. Bubenik. Why do humans get "goosebumps" when they are cold, or under other circumstances? [1]

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