Final answer:
The statement is false because muscle contraction ends when nerve signaling ends and the SR reabsorbs calcium ions, not synaptic vesicles. Calcium is important for both muscle contraction and maintaining muscle tone even after contraction ends.
Step-by-step explanation:
The statement that muscle contraction continues until nerve impulses cease, and calcium ions are returned to their storage sites in synaptic vesicles is false. Muscle contraction continues until signaling from the motor neuron ends, which subsequently causes the cell to repolarize, closing voltage-gated calcium channels in the sarcoplasmic reticulum (SR). ATP-dependent calcium pumps then actively transport Ca++ ions back into the SR and not into synaptic vesicles. Calcium's role in maintaining muscle tone with a low concentration remaining in the sarcoplasm is also important for keeping the muscle slightly contracted.
Nerve impulses lead to the release of the neurotransmitter acetylcholine (ACh), which binds to receptors on the muscle fiber, initiating an action potential that triggers the release of Ca++ from the SR. This release allows for muscle contraction through the binding of calcium to actin, facilitating the sliding of actin and myosin filaments. When signaling ends, the reuptake of Ca++ causes relaxation by allowing tropomyosin to cover the myosin binding sites on actin, preventing further cross-bridging and leading to muscle relaxation.