Goosebumps are small bumps that temporarily appear on the skin in response to certain sensations, such as cold, or to certain emotions, such as fear. Goosebumps get their name from their resemblance to the skin of a goose that has had its feathers plucked. They are also called gooseflesh, goose pimples, chill bumps, or chicken skin. The medical term for this harmless condition is cutis anserina.
In humans, tiny hairs cover most of the skin. Part of each hair extends below the surface of the skin. This part lies in a baglike structure called the follicle. Goosebumps occur when tiny involuntary muscles attached to hair follicles contract or flex. The flexing of these muscles causes small bumps to form on the skin. It also makes the hairs stand up. This is why people with goosebumps may describe the feeling as being like their hair is standing on end.
The muscle contractions are triggered by a part of the nervous system called the sympathetic nervous system. The sympathetic nervous system responds to the body’s needs during increased activity and in emergencies. Animals with fur on their bodies raise their hairs to preserve body heat in cold weather. The raised hairs trap more air to create additional insulation. The bristling of the hairs brought on by fear can make an animal appear larger to enemies. In humans, who have much less body hair, goosebumps no longer serve such purposes.
