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 these

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

Human hair erection (goosebumps) is caused by arrector pili muscles, which are smooth (unstriated) muscles attached to hair follicles. When they contract, hair stands up. Striated muscles are voluntary muscles like skeletal muscles, not involved in this reflex.