A team of scientists from Harvard have discovered a new mechanism in the functioning of the scalp of human skin. They searched for the reasons for the formation of “goose skin” or the characteristic chills the body, but in the end came to the stem cells. And found that between this reflex action and depth control regeneration of hair is a direct connection.
When the outside gets cold, the sympathetic nerves send a signal to a clump of muscle that connects the hair follicle with skin. Muscles contract, the follicle moves, the skin produces the characteristic swelling, and protruding from his hair rises above the skin. The practical effect of no, because hair man for a long time too rare to rampant hair formed heat shield. In animals with thick fur it works, but not in humans.
But why, in the course of evolution we lost hair on the body, but not get rid of this relic? Probably the reason that goose bumps is just part of reaction, fast phase. The same sympathetic nerve when viewed under the electron microscope appeared to be associated with stem cells in the hair follicle. And actually triggering need in order to start the process of hair regeneration, to stimulate their rapid growth and increase in volume.
Scientists came to the conclusion that this two-stage mechanism, and activates both stages one sympathetic nerve. Goose bumps – this is an information message, the message body that was dangerously cold and we need to take action. But relying only on them is too risky, so at once, in parallel, recovering a signal to the hair follicle with instructions to begin the process of regeneration. To the body in response to cold has begun to grow a thick protective coat using stem cells. But that ability man lost long ago, so for us everything is limited to goose bumps.
Source — Harvard