How Does Arrector Pili Occur?

The arrector pili muscles, also knows as hair erector muscles, are small muscles attached to hair follicles in mammals. Contraction of these muscles causes the hairs to stand on end, known colloquially as goose bumps (piloerection).

What causes Arrector Pili contracting?

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 Arrector Pili?

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. The contraction of the muscle is then involuntary stresses such as cold, fear etc.