If a muscle undergoes rapid contraction and relaxation the sarcoplasmic reticulum extension

Options

(a) Requires constant plugging in and out of Ca²⁺
(b) Rapid synthesis of myosin
(c) Do not require energy
(d) All of the above

Correct Answer:

Requires constant plugging in and out of Ca²⁺

Explanation:

Sarcoplasmic reticulum is specialized smooth endoplasmic reticulum of muscle cells which stores Ca⁺⁺ ions. During contraction phase of muscle, Ca⁺⁺ ions are released from sarcoplasmic lumen to sarcoplasm and during relaxation phase of muscle, Ca⁺⁺ ions are pumped back into lumen. Hence, if a muscle undergoes rapid contraction and relaxation it requires constant plugging in and out of Ca⁺⁺ ions from sarcoplasmic reticulum.