The period during the cardiac cycle when cells cannot respond to a stimulus, no matter how strong, is called the _____ period
a. depolarized
b. supranormal
c. relative refractory
d. absolute refractory
D
During the absolute refractory period, the cell will not respond to further stimulation. This means that the myocardial working cells cannot contract and the cells of the electrical conduction system cannot conduct an electrical impulse—no matter how strong the stimulus. As a result, tetanic (sustained) contractions cannot be provoked in cardiac muscle. On the ECG, the absolute refractory period corresponds with the onset of the QRS complex to the peak of the T wave.
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