A reflex that produces a creepy sensation or goose bumps is called the pilomotor reflex. As a result of stimulation of sensitive peripheral nerves emanating directly from the spinal cord, the autonomic peripheral nerve endings are excited, which are responsible for the contraction of the smooth muscles of the hair follicles. By contracting, the muscles of the follicles raise the hairs on the body of the body - the effect of piloerection is observed.
The pilomotor reflex is inherent not only in humans, but also in many other mammals. In reaction to cold, the raised hairs cause the layer of air that has been warmed up by the body to be retained at the surface of the skin. When reacting to danger, the raised coat makes the animals outwardly more massive and gives an intimidating appearance. This reaction is often observed in chimpanzees, frightened or irritated mice, cats, dogs. The porcupine is known for just a manifestation of the pilomotor reflex, as a result of which spines (modified hair) on its back rise up when danger arises.
In humans, the piloerection effect can often be caused not only by cold or fear, but also by other strong emotions caused, for example, by beautiful music, or, conversely, by the grinding of chalk on a board or metal on glass, a feeling of satisfaction or pleasure in something, sexual arousal. ... Piloerection in humans is a rudimentary reflex - due to the limited hairline, it has lost its practical meaning for humans.
The name "goose bumps" really comes from a comparison with goose skin. Geese feathers grow from seals in the epidermis that resemble human hair follicles. After the goose feathers are pulled out, protrusions remain in their places.
The frequent designation of this effect as goosebumps is associated with a comparison with certain species of small insects running around the body - ants, small insects.