arrector pili

(noun)

Any of the small muscles attached to hair follicles in mammals; when the muscles contract they cause the hairs to stand on end.

Related Terms

  • homeostasis
  • vasoconstriction
  • Evaporation

Examples of arrector pili in the following topics:

  • Thermoregulation

    • This is caused by tiny muscles under the surface of the skin, called arrector pili muscles.
    • The arrector pili muscles contract (piloerection) and lift the hair follicles upright.
  • Heat Conservation and Dissipation

    • Mammals have a residual effect from shivering and increased muscle activity: arrector pili muscles create "goose bumps," causing small hairs to stand up when the individual is cold; this has the intended effect of increasing body temperature.
  • Vestigial Structures

    • The arrector pili muscle, which is a band of smooth muscle that connects the hair follicle to connective tissue, contracts and creates the goose bumps on skin.
  • Hair

    • They help comprise the arrector pili muscle that causes the hairs on our body to stand on their ends when we’re cold or we’re scared.  
  • Adrenergic Neurons and Receptors

  • Pili

  • Pili and Pilus Assembly

    • All pili are primarily composed of oligomeric pilin proteins.
    • Pili are antigenic.
    • Specific host responses to old pili structure are not effective on the new structure.
    • Recombination genes of pili code for variable (V) and constant (C) regions of the pili (similar to immunoglobulin diversity).
    • Some pili, called "type IV pili," generate motile forces.
  • Development of the Integumentary System

    • The integument also includes appendages, primarily the sweat and sebaceous glands, hair, nails and arrectores pillorum (tiny muscles at the root of each hair that cause goose bumps).
  • Gene Inversion

    • Fimbrial adhesion by the type I fimbriae in E. coli undergoes site specific inversion to regulate the expression of fimA, the major subunit of the pili, depending on the stage of infection.
  • Gammaproteobacteria

    • Wild-type pili are clearly visible as 7 nm fibres that form bundles @ 0.2Ð0.3 µm wide and 3Ð6 µm long.
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