Question 1
The second heart sound is heard during which phase of the cardiac cycle?
◦ isovolumetric contraction
◦ ventricular ejection
◦ ventricular filling
◦ isovolumetric relaxation
Question 2
If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid, ________.
◦ tetanic contraction would occur due to the short absolute refractory period of cardiac muscle
◦ heart rate would decrease, but blood pressure would rise due to the excess sodium present
◦ threshold is reached more quickly and heart rate would increase
◦ potassium channels compensate and no change in heart rate would occur