NTA Cardiovascular Anatomy and Physiology 1 — Questions and Answers
Question 1: Which structure initiates the normal electrical impulse of the heart?
- Atrioventricular (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, is the heart's primary pacemaker and initiates the normal electrical impulse.
Question 2: What is the normal intrinsic rate of the AV node when it acts as a secondary pacemaker?
- 20–40 bpm
- 40–60 bpm (Correct answer)
- 60–100 bpm
- 100–120 bpm
Correct answer: 40–60 bpm
The AV node has an intrinsic rate of 40–60 bpm, slower than the SA node, which normally suppresses it.
Question 3: Which layer of the heart wall is responsible for the pumping action?
- Epicardium
- Endocardium
- Pericardium
- Myocardium (Correct answer)
Correct answer: Myocardium
The myocardium is the thick muscular middle layer of the heart wall that contracts to pump blood.
Question 4: Deoxygenated blood from the body returns to which heart chamber first?
- Left atrium
- Left ventricle
- Right atrium (Correct answer)
- Right ventricle
Correct answer: Right atrium
Systemic venous blood returns via the superior and inferior vena cava into the right atrium.
Question 5: What is the primary function of the tricuspid valve?
- Prevents backflow from the aorta into the left ventricle
- Prevents backflow from the pulmonary artery into the right ventricle
- Prevents backflow from the left ventricle into the left atrium
- Prevents backflow from the right ventricle into the right atrium (Correct answer)
Correct answer: Prevents backflow from the right ventricle into the right atrium
The tricuspid valve sits between the right atrium and right ventricle, preventing regurgitation during ventricular contraction.
Question 6: The electrical impulse is delayed at the AV node primarily to:
- Increase heart rate during stress
- Allow the ventricles to fill completely before contracting (Correct answer)
- Trigger repolarization of the atria
- Increase myocardial oxygen consumption
Correct answer: Allow the ventricles to fill completely before contracting
The AV node delay (0.12–0.20 sec) allows time for atrial contraction to complete ventricular filling before ventricular systole.
Question 7: Which coronary artery most commonly supplies the SA node?
- Left anterior descending (LAD) artery
- Left circumflex artery
- Right coronary artery (RCA) (Correct answer)
- Posterior descending artery
Correct answer: Right coronary artery (RCA)
In approximately 60% of people the SA node is supplied by the right coronary artery, making RCA occlusion a cause of SA node dysfunction.
NTA Cardiovascular Anatomy and Physiology 1
Which structure initiates the normal electrical impulse of the heart?