NU110 Exam 2 Actual Exam Style V2 | NU
110 Integrated Human Sciences | Galen
1. Which structure is known as the primary pacemaker of the heart?
A. AV node
B. Purkinje fibers
C. SA node
D. Bundle of His
Correct Answer: C
Expert Explanation: The SA node is the primary pacemaker because it possesses the
highest intrinsic rate of depolarization. It is located in the superior wall of the right atrium
and initiates the electrical impulse for each heartbeat. This rhythm is known as sinus
rhythm and typically ranges from 60 to 100 beats per minute.
2. Which valve prevents the backflow of blood from the right ventricle into the right atrium?
A. Tricuspid valve
B. Mitral valve
C. Pulmonary valve
D. Aortic valve
Correct Answer: A
,Expert Explanation: The tricuspid valve is an atrioventricular valve located on the right
side of the heart. It opens to allow blood flow into the ventricle and closes during
ventricular systole to prevent regurgitation. This closure contributes to the first heart
sound, often described as ‘lub.’
3. What is the outermost layer of the heart wall called?
A. Myocardium
B. Epicardium
C. Pericardial cavity
D. Endocardium
Correct Answer: B
Expert Explanation: The epicardium is the visceral layer of the serous pericardium that
adheres directly to the heart surface. It consists of a thin layer of connective tissue and
epithelium that protects the heart. The myocardium lies beneath it, while the endocardium
forms the inner lining of the chambers.
4. Which vessel carries deoxygenated blood from the heart to the lungs?
A. Aorta
B. Pulmonary vein
C. Superior vena cava
D. Pulmonary artery
, Correct Answer: D
Expert Explanation: The pulmonary artery is unique because it is one of the few arteries
in the body that carries deoxygenated blood. It exits the right ventricle and branches
toward the left and right lungs for gas exchange. Once oxygenated, blood returns to the
heart via the pulmonary veins.
5. During which phase of the cardiac cycle do the ventricles contract?
A. Atrial diastole
B. Isovolumetric relaxation
C. Ventricular diastole
D. Ventricular systole
Correct Answer: D
Expert Explanation: Ventricular systole is the period of contraction that forces blood out
of the heart and into the great vessels. During this phase, the atrioventricular valves close
to prevent backflow into the atria. Pressure rises within the ventricles until the semilunar
valves are forced open for ejection.
6. How is cardiac output calculated?
A. End-diastolic volume minus end-systolic volume
B. Stroke volume divided by heart rate
C. Blood pressure multiplied by resistance
110 Integrated Human Sciences | Galen
1. Which structure is known as the primary pacemaker of the heart?
A. AV node
B. Purkinje fibers
C. SA node
D. Bundle of His
Correct Answer: C
Expert Explanation: The SA node is the primary pacemaker because it possesses the
highest intrinsic rate of depolarization. It is located in the superior wall of the right atrium
and initiates the electrical impulse for each heartbeat. This rhythm is known as sinus
rhythm and typically ranges from 60 to 100 beats per minute.
2. Which valve prevents the backflow of blood from the right ventricle into the right atrium?
A. Tricuspid valve
B. Mitral valve
C. Pulmonary valve
D. Aortic valve
Correct Answer: A
,Expert Explanation: The tricuspid valve is an atrioventricular valve located on the right
side of the heart. It opens to allow blood flow into the ventricle and closes during
ventricular systole to prevent regurgitation. This closure contributes to the first heart
sound, often described as ‘lub.’
3. What is the outermost layer of the heart wall called?
A. Myocardium
B. Epicardium
C. Pericardial cavity
D. Endocardium
Correct Answer: B
Expert Explanation: The epicardium is the visceral layer of the serous pericardium that
adheres directly to the heart surface. It consists of a thin layer of connective tissue and
epithelium that protects the heart. The myocardium lies beneath it, while the endocardium
forms the inner lining of the chambers.
4. Which vessel carries deoxygenated blood from the heart to the lungs?
A. Aorta
B. Pulmonary vein
C. Superior vena cava
D. Pulmonary artery
, Correct Answer: D
Expert Explanation: The pulmonary artery is unique because it is one of the few arteries
in the body that carries deoxygenated blood. It exits the right ventricle and branches
toward the left and right lungs for gas exchange. Once oxygenated, blood returns to the
heart via the pulmonary veins.
5. During which phase of the cardiac cycle do the ventricles contract?
A. Atrial diastole
B. Isovolumetric relaxation
C. Ventricular diastole
D. Ventricular systole
Correct Answer: D
Expert Explanation: Ventricular systole is the period of contraction that forces blood out
of the heart and into the great vessels. During this phase, the atrioventricular valves close
to prevent backflow into the atria. Pressure rises within the ventricles until the semilunar
valves are forced open for ejection.
6. How is cardiac output calculated?
A. End-diastolic volume minus end-systolic volume
B. Stroke volume divided by heart rate
C. Blood pressure multiplied by resistance
