BIOS 255 EDAPT Week 3 Anatomy & Physiology III Quiz 2026
Chamberlain
1. Which layer of the heart wall is primarily composed of cardiac muscle tissue?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
Answer: B
Rationale: The myocardium is the thick middle layer of the heart wall consisting of cardiac
muscle, responsible for the pumping action.
2. Which heart chamber receives deoxygenated blood from the systemic circuit?
A. Right Atrium
B. Left Atrium
C. Left Ventricle
D. Right Ventricle
Answer: A
Rationale: The right atrium receives deoxygenated blood from the superior vena cava,
inferior vena cava, and coronary sinus.
,3. The ‘pacemaker’ of the heart, where the electrical impulse begins, is the:
A. SA Node
B. Bundle of His
C. Purkinje Fibers
D. AV Node
Answer: A
Rationale: The Sinoatrial (SA) node initiates the electrical impulse that sets the heart’s
rhythm.
4. What occurs during the P wave of an Electrocardiogram (ECG)?
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Answer: B
Rationale: The P wave represents the depolarization of the atria, which leads to atrial
contraction.
5. Which valve prevents the backflow of blood into the left ventricle?
A. Mitral valve
B. Pulmonary semilunar valve
C. Tricuspid valve
D. Aortic semilunar valve
Answer: D
Rationale: The aortic semilunar valve closes when the left ventricle relaxes to prevent
blood from flowing back from the aorta.
, 6. Which vessel carries oxygenated blood from the lungs to the heart?
A. Pulmonary Artery
B. Pulmonary Vein
C. Superior Vena Cava
D. Aorta
Answer: B
Rationale: Unlike most veins, the pulmonary veins carry oxygen-rich blood from the lungs
to the left atrium.
7. The first heart sound (S1 or ‘lub’) is caused by the:
A. Closing of semilunar valves
B. Opening of AV valves
C. Closing of AV valves
D. Opening of semilunar valves
Answer: C
Rationale: S1 is the sound of the Atrioventricular (AV) valves (tricuspid and mitral) closing
at the start of ventricular systole.
8. Which of the following is the thickest chamber of the heart?
A. Left Ventricle
B. Right Ventricle
C. Left Atrium
D. Right Atrium
Answer: A
Rationale: The left ventricle has the thickest muscular wall because it must pump blood
against the high resistance of the entire systemic circuit.
Chamberlain
1. Which layer of the heart wall is primarily composed of cardiac muscle tissue?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
Answer: B
Rationale: The myocardium is the thick middle layer of the heart wall consisting of cardiac
muscle, responsible for the pumping action.
2. Which heart chamber receives deoxygenated blood from the systemic circuit?
A. Right Atrium
B. Left Atrium
C. Left Ventricle
D. Right Ventricle
Answer: A
Rationale: The right atrium receives deoxygenated blood from the superior vena cava,
inferior vena cava, and coronary sinus.
,3. The ‘pacemaker’ of the heart, where the electrical impulse begins, is the:
A. SA Node
B. Bundle of His
C. Purkinje Fibers
D. AV Node
Answer: A
Rationale: The Sinoatrial (SA) node initiates the electrical impulse that sets the heart’s
rhythm.
4. What occurs during the P wave of an Electrocardiogram (ECG)?
A. Ventricular depolarization
B. Atrial depolarization
C. Ventricular repolarization
D. Atrial repolarization
Answer: B
Rationale: The P wave represents the depolarization of the atria, which leads to atrial
contraction.
5. Which valve prevents the backflow of blood into the left ventricle?
A. Mitral valve
B. Pulmonary semilunar valve
C. Tricuspid valve
D. Aortic semilunar valve
Answer: D
Rationale: The aortic semilunar valve closes when the left ventricle relaxes to prevent
blood from flowing back from the aorta.
, 6. Which vessel carries oxygenated blood from the lungs to the heart?
A. Pulmonary Artery
B. Pulmonary Vein
C. Superior Vena Cava
D. Aorta
Answer: B
Rationale: Unlike most veins, the pulmonary veins carry oxygen-rich blood from the lungs
to the left atrium.
7. The first heart sound (S1 or ‘lub’) is caused by the:
A. Closing of semilunar valves
B. Opening of AV valves
C. Closing of AV valves
D. Opening of semilunar valves
Answer: C
Rationale: S1 is the sound of the Atrioventricular (AV) valves (tricuspid and mitral) closing
at the start of ventricular systole.
8. Which of the following is the thickest chamber of the heart?
A. Left Ventricle
B. Right Ventricle
C. Left Atrium
D. Right Atrium
Answer: A
Rationale: The left ventricle has the thickest muscular wall because it must pump blood
against the high resistance of the entire systemic circuit.
