You correctly answered: the long refractory period of the cardiac action potential. 2 Given the function of the heart, why is it important that cardiac muscle cannot reach tetanus? You correctly answered: The ventricles must contract and relax fully with each beat to pump blood. 3 An extrasystole corresponds to You correctly answered: an extra ventricular contraction. 4 Explain why the larger waves seen on the oscilloscope represent the ventricular contraction. Your answer: The reason why ventricular waves have much larger waves than the atrial waves is because the atrium only needs to pump the blood over a very short distance. However, the ventricles of the heart need to pump over a very long distance to circulate the entire body. Thus, the amplitude of the ventricle waves is much larger than the atrial waves. 1 Explain why the amplitude of the wave did not change when you increased the frequency of the stimulation. (Hint: relate your response to the refractory period of the cardiac action potential.) How well did the results compare with your prediction? Your answer: The reason why the amplitude of the wave did not change is because frequency is independent upon the amplitude of the wave. Additionally, the heart has a longer refractory period which prevents the cardiac muscle from wave summation or from reaching tetanus.
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- Winter '20