Goose bumps

What is Goose Skin?

Goose skin, or anserine skin, consists of the transient appearance of small skin reliefs close together; these tiny hills are formed by the reflex, and therefore involuntary, contraction of the erector muscles of the hair, as happens following a cold sudden or emotional factors. Not surprisingly, the term goose skin is synonymous with horripilation, piloerection or pilomotor reflex.

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The term "goose skin" refers to the typical appearance assumed by the skin when piloerection occurs. This aspect, in fact, recalls that of the skin of a plucked "goose", or more generally, of a plucked bird. Not surprisingly, in other countries this phenomenon is referred to as "chicken skin".

How does it manifest itself?

Normally, the hair follicles - as well as the hairs they host - are not straight, but sinking into the skin at a certain angle. By contracting, therefore shortening, the erector muscles of the hair pull their assisted, straightening it and wrinkling the surrounding skin, which visibly lifts giving rise to goose skin. Once the goose skin ends, the hair stems tend to "self-comb" falling back in an orderly manner.
The reflex of the contraction of the piloerector muscles (piloerection) is regulated by the sympathetic nervous system in response to various stimuli of different origin and nature.

Causes

As mentioned, the contraction of the piloerector muscle can be caused by various causes. First of all, we certainly find the body's response to very cold temperatures. In fact, once erect, the hairs retain a layer of air that acts as an insulating cushion, hindering the dispersion of body heat. The same recruitment of the muscle fibers of the erector hair allows to generate a small amount of heat, precious in colder climates. Of course, this type of defensive mechanism to protect themselves from low temperatures is effective only for animals with thick fur, while for the " man has lost its effectiveness with the advancement of evolution and the gradual decrease of body hair.
As for the influence of emotional factors, it is plausible that the goose skin is triggered by the so-called "fight or flight" mechanism (fight or flight, or "fight and flight" mechanism), which is activated in dangerous conditions at the purpose of preparing the body to sustain a sudden and violent effort. Supported by the massive activation of the sympathetic nervous system, with the release of catecholamines, the "fight or flight" mechanism increases the heart rate and contractility, dilates the bronchi, the pupil and the blood vessels of the limbs and the heart. Inserted in this context, the goose skin, in addition to increasing the amount of heat retained by the body, makes the animal take on a larger, more aggressive and vigorous appearance that should make the animal give up. attacker from a possible attack. Let's think for example of porcupines and their ability to straighten their quills when threatened, or cats when they are frightened that raise their hair thus seeming larger than reality.
Probably, even the fact that the goose skin accompanies the perception of a screeching, such as that caused by the chalk passed vehemently on the blackboard, can be related to the state of alarm triggered by the strong auditory stimulus.

Pathologies

Goose skin is not always triggered by emotions, feelings or temperature changes, but it can be the symptom of some pathologies, sometimes even serious ones.
However, in medicine goose skin is a rather rare symptom, common to some diseases such as temporal lobe epilepsy, some brain tumors and autonomic hyperreflexia. Skin conditions that mimic goose skin, but with reddish or purplish reliefs, are represented by keratosis pilare and by "avitaminosis C (scurvy).