Goose bumps

What is the leather of the goose?

Goose skin, or anserine skin, consists of the transient appearance of small skin reliefs close together; these tiny hillocks are formed by the reflex contraction, therefore involuntary, of the erector muscles of the hair, as happens following a sudden cold or emotional factors. It is not by chance that the term goose bumps is synonymous with orripilation, piloerection or pilomotor reflex .

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The word "goose bumps" refers to the typical appearance taken on by the skin when the piloerection occurs. This aspect, in fact, resembles that of the skin of a plucked goose, or more generally, of a plucked bird. Not surprisingly, in other countries this phenomenon is indicated with the words "hen skin".

How does it manifest itself?

Normally, hair follicles - as well as the hairs that they house - are not straight, but sinking into the skin with a certain inclination. By contracting, thus shortening, the erector muscles of the hair pull their own assisted, straightening it and making the surrounding skin wrinkle, which rises visibly giving rise to goose bumps. Once the goose bumps are over, the hair shafts tend to "autopettinarsi" 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 erected, the hair retains a layer of air that acts as an insulating pad, hindering the dispersion of body heat. Moreover, as in the shiver, the very recruitment of the muscle fibers of the hair erectors allows to generate a small amount of heat, precious in colder climates. Naturally, this type of defensive mechanism to protect itself from low temperatures is effective only for animals with thick fur, while for humans it has lost its effectiveness with the progress of evolution and the gradual decrease of body hair.

With regard to the influence of emotional factors, it is plausible that goose bumps are triggered by the so-called "fight or flight" mechanism (fight or escape, 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 release of catecholamines, the "fight or flight" mechanism increases cardiac frequency and contractility, dilates the bronchi, the pupil and the blood vessels of the limbs and heart. Inserted in this context, goose bumps, in addition to increasing the amount of heat retained by the body, make the animal assume a larger, more aggressive and vigorous appearance that should make the attacker give up an attack. For example, we think of porcupines and their ability to prick their spines when they are threatened, or even cats, when they are frightened that they raise their hair, thus seeming to be larger than reality.

Probably, even the fact that goose bumps accompany the perception of a shrill, 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.

diseases

Goose bumps are not always triggered by emotions, feelings or temperature changes, but can be a symptom of some pathologies, sometimes even serious ones.

However, in medicine goose bumps are a rather rare symptom, common to some diseases such as temporal lobe epilepsy, some brain tumors and autonomous hyperreflexia. Skin conditions that mimic goose bumps, but with reddish or purple highlights, are represented by keratosis pilare and avitaminosis C (scurvy).