As a result of the long refractory period generated by __________, cardiac muscle can not exhibit __________.
A. the influx of calcium ions, tetanus (tetanic contractions)
B. the out flow of K+, tetanus (tetanic contractions)
C. the influx of Na+, tetanus (tetanic contractions)
D. the influx of Ca++, recruitment
E. the out flow of K+, recruitment
Ans: A. the influx of calcium ions, tetanus (tetanic contractions)
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