Identifying the inaccurate description of ventricular excitation Steps:

• Recall that the cardiac cycle begins with the sinoatrial (SA) node generating an electrical impulse, which spreads across the atria.
• The impulse reaches the atrioventricular (AV) node, where it is delayed to allow atrial contraction to complete.
• The impulse then travels via the bundle of His and Purkinje fibers, starting at the ventricular apex and spreading upward to the base for efficient contraction.
• Compare statements: 1, 2, 3, and 4 align with conduction steps, but 5 misstates the ventricular excitation path.

Why D is correct:

• Ventricular excitation starts at the apex via Purkinje fibers and sweeps upward to the base, per cardiac conduction physiology, not from the base.

Why the others are wrong:

• A: Impulse does travel through Purkinje tissue during ventricular depolarization.
• B: AV node delays the impulse to coordinate atrial and ventricular contraction.
• C: SA node initiates the impulse (though it doesn't contract; this is a minor phrasing issue, but the event occurs).

Final answer: D