Question

Relaxation of skeletal muscle requires (choose the one correct answer):

A. binding of calcium to troponin
B. Removal of acetylcholine from the receptor on the neuromuscular junction.
C. depolarization of the t tubule
D. high levels of calcium in the muscle cytoplasm

Answer 1

Relaxation of skeletal muscle requires the removal of acetylcholine from the neuromuscular junction (NMJ).

Step-by-step explanation:

Relaxing skeletal muscle fibers begins with the motor neuron ceasing the release of acetylcholine (ACh) at the neuromuscular junction (NMJ). The repolarization of the muscle fiber closes the gates in the sarcoplasmic reticulum (SR), which allows ATP-driven pumps to move calcium ions (Ca++) back into the SR. This reshields the actin-binding sites on the thin filaments, preventing the formation of cross-bridges between the thin and thick filaments and leading to muscle relaxation. Therefore, the correct answer is B. Removal of acetylcholine from the receptor on the neuromuscular junction.