Answer:
Refractory period
Explanation:
When two stimuli are applied one after another intermediately, muscles contract in response to the first stimuli. Once a muscle fiber receives stimulation to contract, it loses its excitability temporarily and cannot respond for a time. This period when the muscle loses its excitability is called refractory period.
Different types of muscle fibers have different duration of refractory period. The refractory period of skeletal muscle is shorter than that of cardiac muscle. During an absolute refractory period, the activation gates of voltage-gated Na+ channels are open and the channels are inactivating while the voltage-gated K+ channels are open.
