Anatomy Exam Anatomy of the Heart 4 — Questions and Answers
Question 1: Which structure initiates the normal cardiac electrical impulse?
- Atrioventricular (AV) node
- Bundle of His
- Purkinje fibers
- Sinoatrial (SA) node (Correct answer)
Correct 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.
Question 2: What type of epithelium lines the inner surface (endocardium) of the heart?
- Simple cuboidal epithelium
- Simple squamous epithelium (endothelium) (Correct answer)
- Stratified squamous epithelium
- Pseudostratified columnar epithelium
Correct answer: Simple squamous epithelium (endothelium)
The endocardium is lined by simple squamous epithelium called endothelium, which is continuous with the endothelium of blood vessels.
Question 3: The left border of the heart is formed primarily by which structure?
- Left atrium
- Right ventricle
- Left ventricle (Correct answer)
- Aortic arch
Correct 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.
Question 4: Chordae tendineae connect papillary muscles to which structures?
- Semilunar valve cusps
- Atrioventricular valve cusps (Correct answer)
- Interventricular septum
- Trabeculae carneae
Correct 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.
Question 5: Which sinus of the pericardium lies behind the left atrium between the pulmonary veins?
- Transverse sinus
- Oblique sinus (Correct answer)
- Coronary sinus
- Anterior sinus
Correct 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.
Question 6: What percentage of ventricular filling occurs passively (without atrial contraction) in a normal resting heart?
- Approximately 20%
- Approximately 50%
- Approximately 70–80% (Correct answer)
- Approximately 95–100%
Correct 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%.
Question 7: The right coronary artery typically gives rise to the posterior descending artery in which type of coronary dominance?
- Left dominant circulation
- Co-dominant circulation
- Right dominant circulation (Correct answer)
- Non-dominant circulation
Correct 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.
Anatomy Exam Anatomy of the Heart 4
Which structure initiates the normal cardiac electrical impulse?