question_answer 33)

  Which muscles act involuntarily? (i) Striated muscles          (ii) Smooth muscles        (iii) Cardiac muscles        (iv) Skeletal muscles (a) (i) and (ii)                     (b) (ii) and (iii)                     (c) (iii) and (iv)                  (d) (i) and (iv)

Answer:

  (b) Smooth muscles are found in the walls of hollow visceral organs. They do not work according to our will. They are involved in peristaltic movements of gastro intestinal tract and male genital tract. Cardiac muscles are present in the heart. They contract and relax rapidly, rhythmically and tirelessly. They help to pump the blood to various parts of the body. The working of both smooth and cardiac muscles is involuntary while skeletal or straited muscles move according to our will and are voluntary in action.