At which of the following levels does the base of the heart lie?

Correct Answer: B

Rationale: The base of the heart lies at the level of the T5-T7 vertebrae, formed primarily by the atria, as it sits on the diaphragm.

Correct Answer: C

Rationale: Tricuspid valve stenosis produces a diastolic murmur due to obstructed flow during ventricular filling.

Correct Answer: A

Rationale: The SA node has a slow depolarizing phase due to slow calcium influx, unlike the rapid sodium-driven depolarization elsewhere.

Correct Answer: B

Rationale: High cholesterol inhibits HMG CoA reductase to reduce further synthesis.

Correct Answer: C

Rationale: Vasculitis causes noninfectious myocarditis, unlike the infectious agents listed.