Exercise 6: Cardiovascular Physiology: Activity 1: Investigating the Refractory Period of Cardiac Muscle Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. The cardiac muscle is capable of which of the following? You correctly answered: c. autorhythmicity 2. Phase 2 of the cardiac action potential, when the calcium channels remain open and potassium channels are closed, is called the You correctly answered: a. plateau phase. 3. Which of the following
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Which of the following do you think contribute to the inability of cardiac muscle to be tetanized? You correctly answered: a. the long refractory period of the cardiac action potential 3. Given the function of the heart, why is it important that cardiac muscle cannot reach tetanus? You correctly answered: b. The ventricles must contract and relax fully with each beat to pump blood. 4. An extrasystole corresponds to You correctly answered: c. an extra ventricular contraction.
Review Sheet Results 1. Explain why the larger waves seen on the oscilloscope represent the ventricular contraction. Your answer: The ventricles are larger domiciliate which is why, when they contract they create more force thus making a bigger wave. 2. 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 maximum threshold will not change in cardiac muscle cells (as with any other cells), which is determined by the X amount of voltage needed for calcium channels to open. After this point, no additional voltage can cause the channels to open more, or again, prior to depolarization.
3. Why is it only possible to induce an extrasystole during relaxation? Your answer: cardiac is able to depolarize only after