Cardiac Anatomy & Physiology Flashcards

During isovolumetric contraction, which valves are closed?

Answer: Both AV and semilunar valves closed

During isovolumetric contraction, all four valves are closed as ventricular pressure rises before it exceeds outflow vessel pressure.

Which coronary artery is most commonly implicated in anterior wall myocardial infarction?

Answer: Left anterior descending artery

The left anterior descending (LAD) artery supplies the anterior wall and apex; occlusion causes anterior MI.

The tricuspid valve normally has how many leaflets?

Answer: Three

The tricuspid valve has three leaflets: anterior, posterior, and septal, separating the right atrium from the right ventricle.

Which of the following increases myocardial oxygen demand (MVO₂)?

Answer: Increased wall stress (Laplace)

Myocardial oxygen demand increases with elevated wall stress (pressure × radius / wall thickness), heart rate, and contractility.

In a normally functioning heart, which event immediately precedes the opening of the mitral valve?

Answer: Isovolumetric relaxation

After isovolumetric relaxation, ventricular pressure falls below atrial pressure, causing the mitral valve to open and filling to begin.

Which of the following describes the function of the pericardium?

Answer: Provides a protective sac and limits acute cardiac dilation

The pericardium protects the heart, reduces friction, and via the pericardial constraint effect limits acute overdistension.

Which ion is primarily responsible for the plateau phase (phase 2) of the cardiac action potential?

Answer: Calcium (Ca²⁺) influx via L-type channels

The plateau phase of the ventricular action potential is maintained by slow L-type calcium channel influx balanced against potassium efflux.