CCT Cardiac Anatomy & Physiology 3 — Questions and Answers
Question 1: During isovolumetric contraction, which of the following best describes the state of the heart valves?
- AV valves open, semilunar valves closed
- AV valves closed, semilunar valves open
- All valves open
- All valves closed (Correct answer)
Correct answer: All valves closed
During isovolumetric contraction, all four valves are closed as ventricular pressure rises but has not yet exceeded aortic or pulmonary pressure to open semilunar valves.
Question 2: The left circumflex artery (LCx) most commonly supplies which region of the heart?
- Anterior left ventricle
- Lateral wall of the left ventricle (Correct answer)
- Right ventricle
- Interventricular septum
Correct answer: Lateral wall of the left ventricle
The left circumflex artery runs in the left atrioventricular groove and primarily supplies the lateral wall of the left ventricle and the left atrium.
Question 3: What does the term 'preload' refer to in cardiac physiology?
- Arterial resistance opposing ventricular ejection
- Ventricular wall tension at end-diastole (Correct answer)
- The force of myocardial contractility
- Heart rate times stroke volume
Correct answer: Ventricular wall tension at end-diastole
Preload refers to the ventricular wall tension (stretch) at end-diastole, which is determined by end-diastolic volume and reflects the degree of myocardial fiber stretch before contraction.
Question 4: Which structure separates the right and left ventricles?
- Interatrial septum
- Crista terminalis
- Interventricular septum (Correct answer)
- Atrioventricular septum
Correct answer: Interventricular septum
The interventricular septum is a thick muscular wall that divides the left and right ventricles and contributes significantly to left ventricular pumping function.
Question 5: What is the primary pacemaker of the heart under normal conditions?
- AV node
- Bundle of His
- Sinoatrial (SA) node (Correct answer)
- Purkinje fibers
Correct answer: Sinoatrial (SA) node
The SA node, located in the right atrium near the superior vena cava, spontaneously depolarizes at the fastest intrinsic rate (~60–100 bpm) and serves as the heart's primary pacemaker.
Question 6: Which great vessel carries deoxygenated blood from the right ventricle to the lungs?
- Aorta
- Pulmonary artery (Correct answer)
- Pulmonary vein
- Superior vena cava
Correct answer: Pulmonary artery
The pulmonary artery (and its right and left branches) carries deoxygenated blood from the right ventricle to the lungs for oxygenation.
Question 7: Starling's Law of the Heart states that stroke volume increases when:
- Heart rate decreases
- End-diastolic volume increases (Correct answer)
- Afterload increases
- Sympathetic tone decreases
Correct answer: End-diastolic volume increases
Frank-Starling's law states that within physiologic limits, increased ventricular filling (end-diastolic volume) stretches the myocardium and increases stroke volume due to enhanced actin-myosin overlap.
CCT Cardiac Anatomy & Physiology 3
During isovolumetric contraction, which of the following best describes the state of the heart valves?