NWCA CET Test 170 Questions and Correct Answers with Rationales |
Fall 2025/2026 Update | 100% Correct
1. Which layer of the heart is responsible for contracting to pump blood?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
Correct Answer:: B. Myocardium
Rationale: The myocardium is the muscular middle layer of the heart wall that contracts to
pump blood through the circulatory system. The epicardium is the outer layer, endocardium
lines the chambers, and pericardium is the sac surrounding the heart.
2. What is the primary function of the tricuspid valve?
A. Prevents backflow from left ventricle to left atrium
B. Prevents backflow from right ventricle to right atrium
C. Prevents backflow from aorta to left ventricle
D. Prevents backflow from pulmonary artery to right ventricle
Correct Answer:: B. Prevents backflow from right ventricle to right atrium
Rationale: The tricuspid valve is located between the right atrium and right ventricle, closing
during ventricular systole to prevent regurgitation of blood.
3. During the cardiac cycle, diastole refers to which phase?
A. Contraction of the ventricles
B. Relaxation of the heart chambers
C. Ejection of blood into the aorta
D. Filling of the atria with blood
Correct Answer:: B. Relaxation of the heart chambers
, Rationale: Diastole is the phase where the heart muscle relaxes, allowing chambers to fill with
blood, while systole is the contraction phase.
4. Which vessel carries oxygenated blood from the lungs to the left atrium?
A. Pulmonary artery
B. Pulmonary vein
C. Aorta
D. Vena cava
Correct Answer:: B. Pulmonary vein
Rationale: The pulmonary veins are the only veins that carry oxygenated blood, transporting it
from the lungs to the left atrium for systemic circulation.
5. What is the role of the sinoatrial (SA) node in the heart?
A. Conducts impulses from atria to ventricles
B. Acts as the primary pacemaker
C. Regulates blood pressure
D. Filters blood in the chambers
Correct Answer:: B. Acts as the primary pacemaker
Rationale: The SA node initiates electrical impulses that set the heart rate, located in the right
atrium.
6. The Bundle of His is located in which part of the conduction system?
A. SA node
B. Interatrial septum
C. Interventricular septum
D. AV node
Correct Answer:: C. Interventricular septum
, Rationale: After leaving the AV node, the impulse travels through the Bundle of His, which
runs along the interventricular septum before splitting into right and left bundle branches.
7. Which valve is heard best at the 2nd right intercostal space?
A. Tricuspid
B. Pulmonary
C. Aortic
D. Mitral
Correct Answer:: C. Aortic
Rationale: Aortic area = 2nd right intercostal space, parasternal border.
8. The left anterior descending (LAD) artery primarily supplies which area of the heart?
A. Inferior wall
B. Anterior wall and septum
C. Lateral wall
D. Right ventricle
Correct Answer:: B. Anterior wall and septum
Rationale: LAD occlusion is the classic “widow-maker” MI affecting the anterior 2/3 of the
septum and anterior left ventricle.
9. What is the normal duration of the QRS complex?
A. 0.12–0.20 sec
B. Less than 0.12 sec
C. 0.20–0.24 sec
D. Greater than 0.24 sec
Correct Answer:: B. Less than 0.12 sec
, Rationale: Normal QRS duration is 0.06–0.10 sec (up to 0.11 sec acceptable). ≥0.12 sec
indicates bundle branch block or ventricular origin.
10. Which coronary artery supplies the SA node in 55–60% of people?
A. Left circumflex
B. Right coronary artery
C. Left anterior descending
D. Posterior descending
Correct Answer:: B. Right coronary artery
Rationale: RCA supplies the SA node in ~60% (left circumflex in the remaining ~40%).
11. Stroke volume is defined as:
A. Heart rate × cardiac output
B. End-diastolic volume – end-systolic volume
C. Cardiac output ÷ heart rate
D. Blood pressure × total peripheral resistance
Correct Answer:: B. End-diastolic volume – end-systolic volume
Rationale: SV = EDV – ESV (normal ~70 mL).
12. The mitral valve is best heard at which location?
A. 2nd left intercostal space
B. 5th left intercostal space, midclavicular line
C. Left lower sternal border
D. Right lower sternal border
Correct Answer:: B. 5th left intercostal space, midclavicular line
Rationale: This is the apex of the heart (mitral/apical area).
Fall 2025/2026 Update | 100% Correct
1. Which layer of the heart is responsible for contracting to pump blood?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
Correct Answer:: B. Myocardium
Rationale: The myocardium is the muscular middle layer of the heart wall that contracts to
pump blood through the circulatory system. The epicardium is the outer layer, endocardium
lines the chambers, and pericardium is the sac surrounding the heart.
2. What is the primary function of the tricuspid valve?
A. Prevents backflow from left ventricle to left atrium
B. Prevents backflow from right ventricle to right atrium
C. Prevents backflow from aorta to left ventricle
D. Prevents backflow from pulmonary artery to right ventricle
Correct Answer:: B. Prevents backflow from right ventricle to right atrium
Rationale: The tricuspid valve is located between the right atrium and right ventricle, closing
during ventricular systole to prevent regurgitation of blood.
3. During the cardiac cycle, diastole refers to which phase?
A. Contraction of the ventricles
B. Relaxation of the heart chambers
C. Ejection of blood into the aorta
D. Filling of the atria with blood
Correct Answer:: B. Relaxation of the heart chambers
, Rationale: Diastole is the phase where the heart muscle relaxes, allowing chambers to fill with
blood, while systole is the contraction phase.
4. Which vessel carries oxygenated blood from the lungs to the left atrium?
A. Pulmonary artery
B. Pulmonary vein
C. Aorta
D. Vena cava
Correct Answer:: B. Pulmonary vein
Rationale: The pulmonary veins are the only veins that carry oxygenated blood, transporting it
from the lungs to the left atrium for systemic circulation.
5. What is the role of the sinoatrial (SA) node in the heart?
A. Conducts impulses from atria to ventricles
B. Acts as the primary pacemaker
C. Regulates blood pressure
D. Filters blood in the chambers
Correct Answer:: B. Acts as the primary pacemaker
Rationale: The SA node initiates electrical impulses that set the heart rate, located in the right
atrium.
6. The Bundle of His is located in which part of the conduction system?
A. SA node
B. Interatrial septum
C. Interventricular septum
D. AV node
Correct Answer:: C. Interventricular septum
, Rationale: After leaving the AV node, the impulse travels through the Bundle of His, which
runs along the interventricular septum before splitting into right and left bundle branches.
7. Which valve is heard best at the 2nd right intercostal space?
A. Tricuspid
B. Pulmonary
C. Aortic
D. Mitral
Correct Answer:: C. Aortic
Rationale: Aortic area = 2nd right intercostal space, parasternal border.
8. The left anterior descending (LAD) artery primarily supplies which area of the heart?
A. Inferior wall
B. Anterior wall and septum
C. Lateral wall
D. Right ventricle
Correct Answer:: B. Anterior wall and septum
Rationale: LAD occlusion is the classic “widow-maker” MI affecting the anterior 2/3 of the
septum and anterior left ventricle.
9. What is the normal duration of the QRS complex?
A. 0.12–0.20 sec
B. Less than 0.12 sec
C. 0.20–0.24 sec
D. Greater than 0.24 sec
Correct Answer:: B. Less than 0.12 sec
, Rationale: Normal QRS duration is 0.06–0.10 sec (up to 0.11 sec acceptable). ≥0.12 sec
indicates bundle branch block or ventricular origin.
10. Which coronary artery supplies the SA node in 55–60% of people?
A. Left circumflex
B. Right coronary artery
C. Left anterior descending
D. Posterior descending
Correct Answer:: B. Right coronary artery
Rationale: RCA supplies the SA node in ~60% (left circumflex in the remaining ~40%).
11. Stroke volume is defined as:
A. Heart rate × cardiac output
B. End-diastolic volume – end-systolic volume
C. Cardiac output ÷ heart rate
D. Blood pressure × total peripheral resistance
Correct Answer:: B. End-diastolic volume – end-systolic volume
Rationale: SV = EDV – ESV (normal ~70 mL).
12. The mitral valve is best heard at which location?
A. 2nd left intercostal space
B. 5th left intercostal space, midclavicular line
C. Left lower sternal border
D. Right lower sternal border
Correct Answer:: B. 5th left intercostal space, midclavicular line
Rationale: This is the apex of the heart (mitral/apical area).
