This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
In humans, where does depolarisation of cardiac ventricular muscle stas from? 
Select and explain. 
A. Posterobasal pa of ventricle, B. Left side of inter ventricular septum, C. Uppermost pa of interventricular septum, D. Basal poion of ventricle
B: Left side of inter ventricular septum
Answer: B: Left side of inter ventricular septum 
Explanation: In humans, depolarization of the ventricular muscle stas at the left side of the interventricular septum and moves first to the right across the mid poion of the septum. The wave of depolarization then spreads down the septum to the apex of the hea. It then returns along the ventricular walls to the AV groove, proceeding from the endocardial to the epicardial surface. The last pas of the hea to be depolarized are the posterobasal poion of the left ventricle, the pulmonary conus, and the uppermost poion of the septum.