Why are we put the hen skin?

The hen skin, or the duck meat that the Englishmen say, is kind of an erizamiento of the pores of the skin that he/she reminds us once to those birds plucked.

But, what does it cause the hen skin? which is the mechanism?

The hen skin is the answer to certain stimuli:
#I startle or fright
#cold
#chill or alteration in the spirit

Although, in fact, the three refer to a descent of corporal temperature, either so much for environmental causes as for internal causes, either for the chills caused by the fear or the nerves or for the intense sentimental sensation as a music an aroma or any other circumstance that it moves us.

The operation is the following one:

In the deepest part in the dermis they are the glands sudoríparas, the fatty fabric, the bulbs pilosos and a fine musculature that it operates on the pores, dilating and contracting those tiny sphincters with the purpose of maintaining the temperature. If there is an excess of heat they open up to liberate perspiration and to contribute to the corporal cooling for evaporation. If there is a lack of heat (I fry) they contract and they close to avoid the loss of more heat.

When this muscular group—called musculus erecting pili or muscle horripilador—he/she contracts, the pore closes, the skin forms a bundle around the follicle and the hair is bristled, giving the hen skin as a result.

This reflection is in the man a resíduo of in the past, because our body is not so covered with hair as in prehistoric time, but in many hairy animals it is a very useful mechanism to maintain the heat, because when being bristled the coat he/she swells in its group and it provides an insulating layer of much more size.

On the other hand, the fright or fright that it unchains this mechanism are part of the answer of to escape or to fight that it is presented before a threat. The erizamiento of the hair provides a bigger size that he/she helps to intimidate the opponent. In this respect remembering the hair erizamiento and the snorts of a threatened cat, the erect posture of the bear or the membranes of the neck of the lizard of Kingy (yes, for that reason it accompanies an image from the lizard to this entrance, for if he/she asked it to him some onlooker), dedicated artifices all them to offer a more lowering aspect. As the one that you/they should offer our ancestros with the bristled corporal body hair.