Exemplar Problems

Question 1

Describe the role of ATP in muscle contraction and relaxation.

Solution: ATP plays a crucial role in both muscle contraction and relaxation. During contraction, it provides the energy needed for the myosin heads to detach from the actin filaments after the power stroke, enabling the myosin heads to return to their original position (re-cocking) for another cycle of contraction. In relaxation, ATP is used to actively pump calcium ions back into the sarcoplasmic reticulum, which reduces the calcium concentration around the actin and myosin filaments, leading to muscle relaxation. Additionally, ATP is involved in breaking down acetylcholine in the synaptic cleft, halting the signal for muscle contraction.