CCS Cardiac Anatomy & Physiology 4

Question 1

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

Accepted Answer

Pulmonary (pulmonic) valve

Answer

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

Question 2

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

Accepted Answer

Right bundle branch

Answer

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

Question 3

Afterload on the left ventricle is best approximated clinically by:

Accepted Answer

Systemic vascular resistance (SVR)

Answer

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

Question 4

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

Accepted Answer

Calcium (Ca2+) influx via L-type channels

Answer

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

Question 5

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

Accepted Answer

Foramen ovale

Answer

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

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