How does goosebumps form

Suddenly, you hear a song from a long time ago, the song your grandmother used to sing to you when you were a child.

Again, you feel a chill on your back and again, you get goosebumps. Why do such seemingly unrelated events elicit the same body reaction? The reason for this is the physiology of emotions. Goosebumps are a physiological phenomenon inherited from our animal ancestors, which was useful to them but are not of much help to us. Goosebumps are tiny elevations of the skin that resemble the skin of poultry after the feathers have been plucked.

Therefore we could as well call them "turkeybumps" or "duckbumps. Each contracting muscle creates a shallow depression on the skin surface, which causes the surrounding area to protrude. The contraction also causes the hair to stand up whenever the body feels cold. In animals with a thick hair coat this rising of hair expands the layer of air that serves as insulation. The thicker the hair layer, the more heat is retained. In people this reaction is useless because we do not have a hair coat, but goosebumps persist nevertheless.

In addition to cold, the hair will also stand up in many animals when they feel threatened--in a cat being attacked by a dog, for example. Everyone experiences goosebumps from time to time.

When it happens, the hairs on your arms, legs, or torso stand up straight. The hairs also pull up a little bump of skin, the hair follicle, up with them. The medical terms for goosebumps are piloerection, cutis anserina, and horripilation. They also form when you experience a strong emotional feeling, such as extreme fear, sadness, joy, and sexual arousal.

This is because the physical exertion activates your sympathetic, or instinctual, nervous system. Sometimes, goosebumps may crop up for no reason at all. Many animals also experience what could be categorized as goosebumps, including porcupines and dogs. On the most basic level, goosebumps can help keep you warm.

In animals, this action also raises hairs in a way that traps air to create insulation. Humans have much less body hair than many other nonhuman animals with hair.

As your body heats up, your goosebumps will slowly begin to disappear. The same goes for bodily exertions that can cause goosebumps, such as having a bowel movement.

After a bowel movement, goosebumps will disappear. Two common responses include increased electrical activity in the muscles just under the skin and increased depth or heaviness of breathing. Goosebumps are the result of tiny muscles flexing in the skin, making hair follicles rise up a bit.

This causes hairs to stand up. Goosebumps are an involuntary reaction: nerves from the sympathetic nervous system — the nerves that control the fight or flight response — control these skin muscles. In the animal kingdom, a threatened animal has a similar reaction, causing fur to be puffed out a bit.

This makes the animal appear bigger and more dangerous. Perhaps the most dramatic example is the porcupine, which puffs out its quills when sensing danger. This can make a threatening adversary think twice before attacking. That may explain why the sympathetic nervous system controls goosebumps — the reflex is tied into the fight or flight response.

Researchers studying mice recently linked goosebumps to the regeneration of hair and hair follicles.

It seems that the nerves connected to the tiny muscles responsible for goosebumps also connect to hair follicle stem cells, which are the cells responsible for hair growth.

So, in response to cold, the nerve tells the tiny muscles in the skin to contract causing goosebumps and the same nerve activates hair follicle stem cells for new hair growth.

They may do this in several ways. Each of these might be more important for furry animals than for humans. Goosebumps may be one of those leftovers from our evolutionary ancestors like the coccyx, or tailbone that serve no important purpose. The new discovery linking goosebumps with hair follicle stem cells might be explained as a longer-term response to cold, at least for animals with fur: they get goosebumps or the animal equivalent in the short run to conserve heat, and thicker fur to keep warmer in the long term.

Most people associate goosebumps with unpleasant situations, such as feeling particularly cold or feeling afraid. Yet there is more to it than that. The arrectores pilorum are hooked up to the sympathetic nervous system, and the sympathetic nervous system has input from many parts of the brain, including those involved with motivation, arousal, and emotion. So other stimuli may cause goosebumps, for instance:.

Though rare, goosebumps can be a sign of a seizure disorder called temporal lobe epilepsy, a disorder of the sympathetic nervous system, or other brain disorders. They are also common during heroin or other opiate withdrawal. In fact, one explanation for the origin of the expression "quitting cold turkey" is that goose bumps that develop during withdrawal from heroin mimic cold turkey flesh. They are a universal but poorly understood phenomenon, but our understanding is improving.