Multiple choice

Human hair is erectile due to action of _______.

  1. unstraited pili muscles

  2. striated pili muscles

  3. Both 1 and 2

  4. None of the above

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Arrector pili muscles are smooth muscles (unstriated) attached to hair follicles. When they contract, hair stands erect (goosebumps). Striated muscles are skeletal muscles under voluntary control, not involved in this involuntary reflex.