Cardiac Cycle Statements Evaluation

Steps:

• Statement 1: Atrioventricular valves open during atrial systole to allow blood flow into ventricles; they close at ventricular systole onset. Incorrect.
• Statement 2: Left and right ventricles contract simultaneously in ventricular systole for coordinated pumping. Correct.
• Statement 3: Delay occurs at atrioventricular node after sinoatrial node impulse; "atrial delay from AV node" misstates pathway and location. Incorrect.
• Statement 4: Electrical impulses conduct rapidly via Purkinje fibers to ventricular myocardium for synchronized contraction. Correct.

Why C is correct:

• Selects statements 2 and 4, aligning with cardiac conduction system physiology where ventricles contract together and Purkinje fibers distribute impulses.

Why the others are wrong:

• A includes incorrect statements 1 and 3 on valve timing and impulse delay.
• B includes incorrect statement 1 on valve closure.
• D includes incorrect statement 3 on impulse pathway.

Final answer: C