What is piloerection?

Piloerection is a term that refers to the involuntary contraction of the erector muscles of the hair follicles and that causes the hair to stand up on the skin. It is what happens when we get "goosebumps" and is considered a physiological response to cold air and extreme emotions, especially fear. In medicine it is also known as cutis anserina.

What function does it have?

Piloerection is a physiological response common in most mammals when faced with a dangerous situation. For example, we all know the piloerection that occurs in the cat in a threatening situation. The cat's fur "puffs up" and makes it appear larger and stronger, which can intimidate your opponent. This reaction can be observed in many other mammals such as chimpanzees, porcupines, rats, otters, etc.

Piloerection also occurs as cold response; As body hair rises, an air chamber is formed that helps retain heat.

Throughout evolution, human beings have been losing most of their body hair and piloerection no longer represents any real advantage as a method of defense and is very low against the cold. For this reason, piloerection in humans is generally considered an evolutionary vestige.

How is it produced?

Piloerection is a sympathetic nervous system reaction, also called adrenergic or noradrenergic system (its main neurotransmitter is norepinephrine). The activation of the sympathetic nervous system is related to the response to those known as E-situations (escape, stress, exercise, emergency) in which there is a release of adrenaline from the adrenal glands directly into the bloodstream. One of its many effects is the piloerector reflex.

In response to cold, activation of the sympathetic nervous system increases muscle activity, being able to make us shiver, which generates more heat. The action on the circulatory system redirects the blood to internal areas to reduce heat loss out through the skin and into the hair follicles causes contraction of the piloerector muscle to form an air chamber to increase insulation.

As a response to dangerous situations, the sympathetic nervous system prepares us to flee or fight. The heart rate increases, more blood is conducted to the large muscle groups, and the pupils dilate, sharpening vision. Piloerection can also occur at these times. intense emotionsproduced even when watching a movie or listening to music, can activate the piloerector response by activating the sympathetic nervous system through emotions.

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