Question

It is important to note, however, that ECGs record the electrical currents generated by cardiac muscle indirectly. They measure the electrical activity present in body fluids from the cardiac impulse that reaches the body surface. What other aspect of this method should one remember when analyzing ECGs?

a. Leads can detect separate potentials from ventricular depolarization and atrial repolarization.

b. Orientation of the electrodes on the body surface can affect the output in an ECG.

c. It follows the activity of a single action potential in a single cell at a single point in time.

Answer 1

Here the correct answer is option (b) orientation of electrodes on the body surface can affect the output in an ECG.

Explaination option (A) is incorrect because ventricular depolarisation and atrial repolarization both occur at the same time that is during QRS complex. Hence leads can not detect separate potential from ventricular depolarisation and atrial repolarization.

option (C) is incorrect because ECG detects action potential in all the cardiac cells together at one point of the time not one cell at a time hence it doesn't follows single action potential in single cell at single point of time.