Why Does the Arrector Pili Muscle Contract?

Arrector Pili Muscle - This is a tiny muscle that attaches to the base of a hair follicle at one end and to dermal tissue on the other end. In order to generate heat when the body is cold, the arrector pili muscles contract all at once, causing the hair to "stand up straight" on the skin.

What stimulates for the Arrector pili to contract?

Each arrector pili is composed of a bundle of smooth muscle fibres which attach to several follicles and is innervated by the sympathetic branch of the autonomic nervous system. ... may stimulate the sympathetic nervous system and thus cause contraction.

What happens when Arrector Pili eye muscles contract?

Contraction of these muscles causes the hairs to stand on end, known colloquially as goose bumps (piloerection).