This viva is about principles of electrophysiology in relation to the heart. 
Q 1 Draw the cardiac action potential for a ventricular muscle cell.
Subsequent questions sought knowledge of what is the Resting Membrane Potential and how is 
it created, to describe ionic mechanism for each of the phases of the ventricular action potential, 
to draw the SA node action potential, compare and contrast the ventricular and SA node action 
potentials, and which pharmacological agents affect the different phases of the pacemaker