CCI Cardiac Anatomy and Physiology 3 — Questions and Answers
Question 1: Which structure separates the right and left atria and may harbor a patent foramen ovale (PFO) in adults?
- Fossa ovalis (Correct answer)
- Crista terminalis
- Eustachian valve
- Moderator band
Correct answer: Fossa ovalis
The fossa ovalis is a thin fibromuscular remnant of the foramen ovale in the interatrial septum; incomplete fusion leaves a PFO, present in ~25% of adults.
Question 2: Cardiac output is calculated as:
- Heart rate × end-diastolic volume
- Stroke volume ÷ heart rate
- Heart rate × stroke volume (Correct answer)
- Mean arterial pressure ÷ systemic vascular resistance
Correct answer: Heart rate × stroke volume
Cardiac output (CO) equals heart rate (HR) multiplied by stroke volume (SV), representing the total volume of blood pumped per minute.
Question 3: Which type of cardiomyocytes has the fastest intrinsic depolarization rate and therefore sets the heart's rhythm?
- Purkinje fibers
- Bundle of His cells
- AV nodal cells
- Sinoatrial nodal cells (Correct answer)
Correct answer: Sinoatrial nodal cells
SA nodal cells depolarize spontaneously at 60–100 times per minute, the fastest of all pacemaker cells, making them the dominant cardiac pacemaker.
Question 4: Which valve is bicuspid (has two leaflets)?
- Tricuspid valve
- Pulmonic valve
- Aortic valve
- Mitral valve (Correct answer)
Correct answer: Mitral valve
The mitral (bicuspid) valve has two leaflets — the anterior and posterior — and guards the left atrioventricular orifice.
Question 5: The aortic valve opens when left ventricular pressure exceeds:
- Left atrial pressure
- Pulmonary artery diastolic pressure
- Aortic diastolic pressure (Correct answer)
- Right ventricular systolic pressure
Correct answer: Aortic diastolic pressure
The aortic valve opens once rising LV systolic pressure surpasses aortic diastolic pressure (approximately 80 mmHg at rest), allowing blood ejection into the aorta.
Question 6: Which portion of the interventricular septum is thinnest and most commonly involved in membranous ventricular septal defects?
- Muscular septum
- Trabecular septum
- Membranous septum (Correct answer)
- Inlet septum
Correct answer: Membranous septum
The membranous septum is the small fibrous upper portion of the interventricular septum and is the most common site for congenital ventricular septal defects.
Question 7: During diastole, the left ventricle fills primarily due to which mechanism in early diastole?
- Active atrial contraction
- Positive intrathoracic pressure
- Ventricular suction from elastic recoil (Correct answer)
- Gravitational flow from pulmonary veins
Correct answer: Ventricular suction from elastic recoil
Early diastolic LV filling is driven largely by active ventricular relaxation (lusitropy) and elastic recoil, creating a suction effect that draws blood from the left atrium.
CCI Cardiac Anatomy and Physiology 3
Which structure separates the right and left atria and may harbor a patent foramen ovale (PFO) in adults?