Question

Which of the following ions has a regulatory role in internal movements?

• A. Calcium
• B. Magnesium
• C. Iron
• D. Zinc

Answer 1

The correct option is A Calcium

• Sarcoplasmic reticulum is similar to endoplasmic reticulum present in other cells. It is present in sarcoplasm (cytoplasm of the muscle cell) of the muscle fiber (muscle cell).
• The main function of the Sarcoplasmic reticulum is to store calcium ions (Ca${}^{2+}$).
• When nerve signal reaches the neuromuscular junction it triggers the release of calcium from sarcoplasmic reticulum which in turn facilitates muscle contraction by binding to troponin. thus causing tropomyosin to shift from the face of the actin filament to which myosin heads need to bind to produce a contraction.
• Hence Calcium ions have a regulatory role in internal movements.
• So, the correct answer is 'Calcium'.