Question

Arrector pili muscles in human are
A) Voluntary
B) Involuntary
C) Voluntary and involuntary
D) None of the above

Answer 1

Arrector pili muscles are found attached to the hair follicles in mammals. When these muscles contract the hair tends to stand, and this phenomenon is commonly known as goosebumps.

Complete answer:
Before finding the correct answer, let us first know a little more about arrector pili muscle. This muscle is found attached to the base of the hair follicle. It is attached to the hair follicle at one end and is attached to the dermal tissue on the other end.

Option A: Voluntary means that it is under our control. When we experience fear, anxiety, etc, the hair stands on one end on its own without us consciously doing or commanding it. Therefore, arrector pili muscles are not voluntary. Thus, this is the incorrect option.
Option B: Involuntary means it is not under our control. When these muscles contract, it leads to hair to stand on one end. Such situations arise when the person is experiencing coldness, anxiety, fear, etc. the standing of hair happens without us commanding. Therefore, arrector pili muscles are involuntary. Thus, this is the correct option.
Option C: These muscles are involuntary as explained above. Thus, this is the incorrect option.
Option D: As one of the options is correct, thus, this is the incorrect option.

Hence the correct answer is option ‘B’.

Note: When the person is experiencing emotions like fear, anxiety, cold signals are sent to the sympathetic nervous system which further sends signals to arrector pili to contract.