Cardiac Anatomy & Physiology Flashcards

Which cardiac structure is responsible for preventing backflow of blood from the pulmonary artery into the right ventricle?

Answer: Pulmonary (pulmonic) valve

The pulmonary valve, a semilunar valve, closes at the end of right ventricular systole to prevent pulmonary regurgitation.

The moderator band (septomarginal trabecula) in the right ventricle carries fibers from which part of the conduction system?

Answer: Right bundle branch

The moderator band carries the right bundle branch across the right ventricular cavity to reach the anterior papillary muscle.

Afterload on the left ventricle is best approximated clinically by:

Answer: Systemic vascular resistance (SVR)

Afterload reflects the resistance the ventricle must overcome to eject blood; SVR is the main clinical surrogate for left ventricular afterload.

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 is maintained by calcium influx through L-type (long-lasting) voltage-gated calcium channels, sustaining contraction.

The fossa ovalis in the interatrial septum is a remnant of which fetal structure?

Answer: Foramen ovale

The fossa ovalis is the adult remnant of the foramen ovale, which allowed right-to-left shunting of blood in the fetal circulation.

Which mechanism accounts for the inotropic effect of increased heart rate (Bowditch effect / Treppe phenomenon)?

Answer: Accumulation of intracellular calcium with successive beats

At higher rates, calcium accumulates intracellularly because there is less time for efflux, enhancing contractility with each successive beat.

The aortic valve is considered bicuspid when congenitally abnormal; normally it has how many cusps?

Answer: Three

The normal aortic valve has three cusps (left, right, and non-coronary/posterior), making it a trileaflet semilunar valve.