Final answer:
Large motor neurons are associated with fast-twitch muscle fibers, which contract quickly and forcefully in response to an action potential. After the contraction, the muscle relaxes and calcium ions are pumped back into the SR.
Step-by-step explanation:
The action potential (AP) associated with large motor neurons leads to the contraction of skeletal muscle fibers. Large motor neurons are associated with fast-twitch muscle fibers, which contract quickly and forcefully in response to an action potential. After the contraction, the muscle relaxes and calcium ions are pumped back into the SR. This neuromuscular event is involved in activating fast-twitch muscle fibers, which are connected to these neurons.
Fast-twitch muscles are designed for quick and forceful actions but fatigue more rapidly than slow-twitch fibers. During a muscle twitch, there are three phases: the latent period, the contraction phase, and the relaxation phase. As the twitch dies away during the relaxation phase, tension in the muscle fiber decreases, calcium ions are reabsorbed into the sarcoplasmic reticulum (SR), and the muscle fiber returns to its resting state.