Define systole and diastole.
What is sinus rhythm, and what is the typical heat beat? Howoften does the SA node fire?
What is an ectopic focus? Give an example. Why is this ofimportance?
The SA node fires spontaneously at regular intervals because ofthe pacemaker potential. How does this potential differ from theresting membrane potential of a neuron or skeletal muscle?
Why is it important that the AV node slow down signal conductionto the ventricles?
Summarize the steps of an action potential of a ventricularcardiomyocyte. A drawing might be helpful (see figure 19.14).
(a) The resting membrane potential of a typical cardiomyocyte is__________.
(b) Which ions participate in theaction potential of these cells? ____________________________
39. What produces the plateau in the action potentials ofcardiomyocytes? Why is this important to the pumping ability of theheart?
Draw a normal electrocardiogram from just before P to just afterT wave (see figure 19.15). Label the waves and intervals. Identifythe portion of the ECG that coincides with each of the followingevents: atrial depolarization, ventricular depolarization,ventricular systole, ventricular repolarization, ventriculardiastole.
