BIOL 252 | BIOL252 Module 1: Human Anatomy &
Physiology II with Lab Updated and Latest
Questions and Correct Answers with Rationale -
Portage Learning
1. Which layer of the heart wall is composed primarily of cardiac muscle tissue and is
responsible for the pumping action?
A. Endocardium
B. Epicardium
C. Myocardium
D. Pericardium
Correct Answer: C
Explanation: The myocardium is the thickest layer of the heart wall and consists of
specialized cardiac muscle cells. This layer provides the necessary force to pump blood
throughout the systemic and pulmonary circuits. The endocardium serves as the smooth
inner lining of the heart chambers and valves. The epicardium is the thin outer layer that
also functions as the visceral pericardium. Understanding these layers helps clinicians
differentiate between conditions like myocarditis and endocarditis.
2. Which valve prevents the backflow of blood from the right ventricle into the right atrium?
A. Aortic valve
B. Mitral valve
C. Tricuspid valve
D. Pulmonary valve
Correct Answer: C
Explanation: The tricuspid valve is an atrioventricular valve located on the right side of
the heart. It closes during ventricular systole to ensure blood moves forward into the
pulmonary trunk. The mitral valve performs a similar function but is located on the left side
of the heart. Semilunar valves, like the aortic and pulmonary valves, prevent backflow into
the ventricles from the great arteries. Proper valve function is essential for maintaining a
unidirectional flow of blood.
3. What is the primary role of the sinoatrial (SA) node in the heart’s conduction system?
A. To delay the electrical impulse before it reaches the ventricles
B. To initiate the electrical impulse that sets the heart rate
,C. To distribute the impulse to the Purkinje fibers
D. To act as the secondary pacemaker when the AV node fails
Correct Answer: B
Explanation: The SA node is known as the natural pacemaker of the heart because it
spontaneously generates electrical impulses. These impulses travel through the atria to
trigger contraction before reaching the AV node. The AV node provides a necessary delay to
allow for ventricular filling. Purkinje fibers are responsible for spreading the impulse
quickly through the ventricular walls. Without the SA node, the heart would rely on slower
latent pacemakers to maintain a heartbeat.
4. During which phase of the cardiac cycle are all four heart valves closed and the ventricles
are contracting?
A. Isovolumetric relaxation
B. Isovolumetric contraction
C. Ventricular filling
D. Ventricular ejection
Correct Answer: B
Explanation: Isovolumetric contraction occurs at the beginning of ventricular systole
when the ventricles start to contract. During this phase, the pressure rises sharply, causing
the AV valves to close while the semilunar valves remain shut. Because no blood is entering
or leaving the ventricles, the volume remains constant. This phase is followed by the
ejection phase once ventricular pressure exceeds arterial pressure. It is a critical period for
building the pressure needed to open the semilunar valves.
5. Which structure carries oxygenated blood from the lungs back to the left atrium?
A. Pulmonary arteries
B. Pulmonary veins
C. Superior vena cava
D. Aorta
Correct Answer: B
Explanation: The pulmonary veins are unique because they carry oxygen-rich blood
toward the heart. Most veins in the systemic circuit carry deoxygenated blood, but the
pulmonary circuit reverses this rule. The pulmonary arteries carry deoxygenated blood
away from the right ventricle toward the lungs. The superior vena cava returns
deoxygenated blood from the upper body to the right atrium. The aorta is the large artery
that distributes oxygenated blood from the left ventricle to the rest of the body.
, 6. What histological feature allows cardiac muscle cells to contract as a single functional unit
or syncytium?
A. Striations
B. Multiple nuclei
C. Intercalated discs
D. Sarcoplasmic reticulum
Correct Answer: C
Explanation: Intercalated discs contain gap junctions and desmosomes that mechanically
and electrically link cardiac cells. Gap junctions allow ions to flow freely between cells,
enabling rapid depolarization across the entire myocardium. This coordination ensures
that the chambers contract simultaneously rather than in a disorganized fashion. While
skeletal muscle is also striated, it lacks these specialized junctional complexes. Thus, the
syncytium property is a hallmark of cardiac muscle physiology.
7. Which of the following describes the Frank-Starling Law of the Heart?
A. Increased heart rate decreases cardiac output
B. The heart rate is primarily regulated by the vagus nerve
C. Increased venous return leads to increased stroke volume
D. The left ventricle pumps more blood than the right ventricle
Correct Answer: C
Explanation: The Frank-Starling Law states that the heart will pump out whatever volume
of blood enters it within physiological limits. As venous return increases, the cardiac
muscle fibers are stretched more, leading to a more forceful contraction. This intrinsic
mechanism helps balance the output of the right and left ventricles. It ensures that the
heart can adapt to changes in physical activity or blood volume. Without this law, blood
would pool in either the systemic or pulmonary circuits.
8. What causes the first heart sound, often described as ‘lub’?
A. The opening of the semilunar valves
B. The closing of the atrioventricular valves
C. The closing of the semilunar valves
D. The flow of blood into the aorta
Correct Answer: B
Explanation: The first heart sound (S1) occurs at the onset of ventricular systole. It is
caused by the turbulence created when the mitral and tricuspid valves snap shut. This
closure prevents blood from flowing back into the atria as the ventricles contract. The
Physiology II with Lab Updated and Latest
Questions and Correct Answers with Rationale -
Portage Learning
1. Which layer of the heart wall is composed primarily of cardiac muscle tissue and is
responsible for the pumping action?
A. Endocardium
B. Epicardium
C. Myocardium
D. Pericardium
Correct Answer: C
Explanation: The myocardium is the thickest layer of the heart wall and consists of
specialized cardiac muscle cells. This layer provides the necessary force to pump blood
throughout the systemic and pulmonary circuits. The endocardium serves as the smooth
inner lining of the heart chambers and valves. The epicardium is the thin outer layer that
also functions as the visceral pericardium. Understanding these layers helps clinicians
differentiate between conditions like myocarditis and endocarditis.
2. Which valve prevents the backflow of blood from the right ventricle into the right atrium?
A. Aortic valve
B. Mitral valve
C. Tricuspid valve
D. Pulmonary valve
Correct Answer: C
Explanation: The tricuspid valve is an atrioventricular valve located on the right side of
the heart. It closes during ventricular systole to ensure blood moves forward into the
pulmonary trunk. The mitral valve performs a similar function but is located on the left side
of the heart. Semilunar valves, like the aortic and pulmonary valves, prevent backflow into
the ventricles from the great arteries. Proper valve function is essential for maintaining a
unidirectional flow of blood.
3. What is the primary role of the sinoatrial (SA) node in the heart’s conduction system?
A. To delay the electrical impulse before it reaches the ventricles
B. To initiate the electrical impulse that sets the heart rate
,C. To distribute the impulse to the Purkinje fibers
D. To act as the secondary pacemaker when the AV node fails
Correct Answer: B
Explanation: The SA node is known as the natural pacemaker of the heart because it
spontaneously generates electrical impulses. These impulses travel through the atria to
trigger contraction before reaching the AV node. The AV node provides a necessary delay to
allow for ventricular filling. Purkinje fibers are responsible for spreading the impulse
quickly through the ventricular walls. Without the SA node, the heart would rely on slower
latent pacemakers to maintain a heartbeat.
4. During which phase of the cardiac cycle are all four heart valves closed and the ventricles
are contracting?
A. Isovolumetric relaxation
B. Isovolumetric contraction
C. Ventricular filling
D. Ventricular ejection
Correct Answer: B
Explanation: Isovolumetric contraction occurs at the beginning of ventricular systole
when the ventricles start to contract. During this phase, the pressure rises sharply, causing
the AV valves to close while the semilunar valves remain shut. Because no blood is entering
or leaving the ventricles, the volume remains constant. This phase is followed by the
ejection phase once ventricular pressure exceeds arterial pressure. It is a critical period for
building the pressure needed to open the semilunar valves.
5. Which structure carries oxygenated blood from the lungs back to the left atrium?
A. Pulmonary arteries
B. Pulmonary veins
C. Superior vena cava
D. Aorta
Correct Answer: B
Explanation: The pulmonary veins are unique because they carry oxygen-rich blood
toward the heart. Most veins in the systemic circuit carry deoxygenated blood, but the
pulmonary circuit reverses this rule. The pulmonary arteries carry deoxygenated blood
away from the right ventricle toward the lungs. The superior vena cava returns
deoxygenated blood from the upper body to the right atrium. The aorta is the large artery
that distributes oxygenated blood from the left ventricle to the rest of the body.
, 6. What histological feature allows cardiac muscle cells to contract as a single functional unit
or syncytium?
A. Striations
B. Multiple nuclei
C. Intercalated discs
D. Sarcoplasmic reticulum
Correct Answer: C
Explanation: Intercalated discs contain gap junctions and desmosomes that mechanically
and electrically link cardiac cells. Gap junctions allow ions to flow freely between cells,
enabling rapid depolarization across the entire myocardium. This coordination ensures
that the chambers contract simultaneously rather than in a disorganized fashion. While
skeletal muscle is also striated, it lacks these specialized junctional complexes. Thus, the
syncytium property is a hallmark of cardiac muscle physiology.
7. Which of the following describes the Frank-Starling Law of the Heart?
A. Increased heart rate decreases cardiac output
B. The heart rate is primarily regulated by the vagus nerve
C. Increased venous return leads to increased stroke volume
D. The left ventricle pumps more blood than the right ventricle
Correct Answer: C
Explanation: The Frank-Starling Law states that the heart will pump out whatever volume
of blood enters it within physiological limits. As venous return increases, the cardiac
muscle fibers are stretched more, leading to a more forceful contraction. This intrinsic
mechanism helps balance the output of the right and left ventricles. It ensures that the
heart can adapt to changes in physical activity or blood volume. Without this law, blood
would pool in either the systemic or pulmonary circuits.
8. What causes the first heart sound, often described as ‘lub’?
A. The opening of the semilunar valves
B. The closing of the atrioventricular valves
C. The closing of the semilunar valves
D. The flow of blood into the aorta
Correct Answer: B
Explanation: The first heart sound (S1) occurs at the onset of ventricular systole. It is
caused by the turbulence created when the mitral and tricuspid valves snap shut. This
closure prevents blood from flowing back into the atria as the ventricles contract. The
