Question

Which of the following statements concerning the role of Ca2+ in the contraction of skeletal muscle is correct?

• A. The mitochondria act as a store of Ca2+ for the contractile process
• B. Ca2+ entry across the plasma membrane is important in sustaining the contraction of skeletal muscle
• C. A rise in intracellular Ca2+allows actin to interact with myosin
• D. The tension of a skeletal muscle fibre is partly regulated by G proteins.

Answer 1

The correct option is C

A rise in intracellular Ca2+allows actin to interact with myosin

The nerve impulse leading to contraction causes an increase in calcium ion concentration in muscle cells. When a muscle is at rest, intracellular calcium is kept low by the continuous action of the calcium pump that moves calcium back into the extracellular fluid