Английская Википедия:Arrector pili muscle
Шаблон:Short description Шаблон:Infobox muscle The arrector pili muscles, also known as hair erector muscles,[1] are small muscles attached to hair follicles in mammals. Contraction of these muscles causes the hairs to stand on end,[2] known colloquially as goose bumps (piloerection).[3]
Structure
Each arrector pili is composed of a bundle of smooth muscle fibres which attach to several follicles (a follicular unit).[4] Each is innervated by the sympathetic division of the autonomic nervous system.[4] The muscle attaches to the follicular stem cell niche in the follicular bulge,[3][4][5] splitting at their deep end to encircle the follicle.[6]
Function
The contraction of the muscle is involuntary. Stresses such as cold, fear etc. may stimulate the sympathetic nervous system, and thus cause muscle contraction.[4]
Thermal insulation
Contraction of arrector pili muscles have a principal function in the majority of mammals of providing thermal insulation.[4] Air becomes trapped between the erect hairs, helping the animal retain heat.
Self defence
Erection of the porcupine's long, thick hairs causes the animal to become more intimidating, scaring predators.Шаблон:Citation needed
Sebum excretion
Pressure exerted by the muscle may cause sebum to be forced along the hair follicle towards the surface, protecting the hair.[7]
Hair follicle stability
Arrector pili muscles also stabilise the base of the hair follicle.[5][6]
Clinical significance
Skin conditions such as leprosy can damage arrector pili muscles, preventing their contraction.[8]
History
The term "arrector pili" comes from Latin. It translates to "hair erector".[1]
Additional images
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Insertion of sebaceous glands into hair shaft
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Cross-section of all skin layers
Notes
- ↑ 1,0 1,1 Шаблон:Cite web
- ↑ Шаблон:Cite book
- ↑ 3,0 3,1 Шаблон:Cite journal
- ↑ 4,0 4,1 4,2 4,3 4,4 Шаблон:Cite journal
- ↑ 5,0 5,1 Шаблон:Cite journal
- ↑ 6,0 6,1 Шаблон:Cite journal
- ↑ Journal of the American Academy of Dermatology Volume 51, Issue 2, August 2004, Pages 217-222 The contribution of the arrector pili muscle and sebaceous glands to the follicular unit structure☆ Enrique Poblet, Francisco Ortega. https://doi.org/10.1016/j.jaad.2004.01.054
- ↑ Шаблон:Cite journal
References
- Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web; https://web.archive.org/web/20110903154915/http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/hair.html
- Шаблон:Cite book
Шаблон:Skin layers and appendages Шаблон:Authority control
