Anatomy of the Heart Flashcards

Which structure initiates the normal cardiac electrical impulse?

Answer: Sinoatrial (SA) node

The SA node, located in the right atrium near the opening of the superior vena cava, is the natural pacemaker that initiates each heartbeat.

What type of epithelium lines the inner surface (endocardium) of the heart?

Answer: Simple squamous epithelium (endothelium)

The endocardium is lined by simple squamous epithelium called endothelium, which is continuous with the endothelium of blood vessels.

The left border of the heart is formed primarily by which structure?

Answer: Left ventricle

The left (obtuse) border of the heart is formed mainly by the left ventricle, with a small contribution from the left auricle superiorly.

Chordae tendineae connect papillary muscles to which structures?

Answer: Atrioventricular valve cusps

Chordae tendineae are tendon-like cords that connect papillary muscles to the cusps of the atrioventricular (mitral and tricuspid) valves, preventing valve prolapse.

Which sinus of the pericardium lies behind the left atrium between the pulmonary veins?

Answer: Oblique sinus

The oblique sinus of the pericardium is a cul-de-sac posterior to the left atrium, bordered by the pulmonary veins and inferior vena cava reflections.

What percentage of ventricular filling occurs passively (without atrial contraction) in a normal resting heart?

Answer: Approximately 70–80%

About 70–80% of ventricular filling occurs passively as blood flows from the atria into the ventricles; atrial contraction ('atrial kick') contributes the remaining 20–30%.

The right coronary artery typically gives rise to the posterior descending artery in which type of coronary dominance?

Answer: Right dominant circulation

In right dominant coronary circulation (approximately 70% of people), the right coronary artery gives rise to the posterior descending artery supplying the inferior heart.