BIOD 152 LAB 4: CARDIOVASCULAR
SYSTEM - THE HEART AND
HEMODYNAMICS QUESTIONS AND
ANSWERS (VERIFIED ANSWERS)
1. Which layer of the heart wall is synonymous with the visceral layer of the serous
pericardium?
A. Endocardium
B. Myocardium
C. Fibrous pericardium
D. Epicardium
Answer: D
Conceptual Explanation: The epicardium is the outermost layer of the heart wall and is
also known as the visceral layer of the serous pericardium.
2. Which structure prevents the atrioventricular valves from everting into the atria during
ventricular systole?
A. Pectinate muscles
B. Chordae tendineae
C. Trabeculae carneae
,D. Crista terminalis
Answer: B
Conceptual Explanation: The chordae tendineae, anchored by papillary muscles, tension
the valve cusps to prevent backflow and eversion into the atria.
3. What is the physiological significance of the 0.1-second delay at the atrioventricular (AV)
node?
A. It allows the ventricles to finish contracting before the atria begin.
B. It allows the atria to complete their contraction and maximize ventricular filling.
C. It ensures the atria have enough time to fill with blood from the veins.
D. It prevents the SA node from firing too rapidly.
Answer: B
Conceptual Explanation: The AV node delay ensures that atrial systole is completed,
pushing the remaining blood into the ventricles before ventricular systole begins.
4. During which phase of the cardiac cycle are all four heart valves closed and the ventricular
volume remains constant while pressure increases?
A. Ventricular filling
B. Ventricular ejection
C. Isovolumetric contraction
D. Isovolumetric relaxation
, Answer: C
Conceptual Explanation: During isovolumetric contraction, the ventricles contract with
both AV and semilunar valves closed, causing a rapid rise in pressure without a change in
volume.
5. Which of the following vessels carries oxygenated blood from the lungs to the left atrium?
A. Pulmonary arteries
B. Superior vena cava
C. Pulmonary veins
D. Coronary sinus
Answer: C
Conceptual Explanation: Unlike most veins, the pulmonary veins carry oxygen-rich blood
from the lungs back to the left side of the heart.
6. The ‘lub’ sound (S1) of the heart is primarily caused by which event?
A. Closure of the semilunar valves
B. Opening of the atrioventricular valves
C. Blood rushing into the aorta
D. Closure of the atrioventricular valves
Answer: D
SYSTEM - THE HEART AND
HEMODYNAMICS QUESTIONS AND
ANSWERS (VERIFIED ANSWERS)
1. Which layer of the heart wall is synonymous with the visceral layer of the serous
pericardium?
A. Endocardium
B. Myocardium
C. Fibrous pericardium
D. Epicardium
Answer: D
Conceptual Explanation: The epicardium is the outermost layer of the heart wall and is
also known as the visceral layer of the serous pericardium.
2. Which structure prevents the atrioventricular valves from everting into the atria during
ventricular systole?
A. Pectinate muscles
B. Chordae tendineae
C. Trabeculae carneae
,D. Crista terminalis
Answer: B
Conceptual Explanation: The chordae tendineae, anchored by papillary muscles, tension
the valve cusps to prevent backflow and eversion into the atria.
3. What is the physiological significance of the 0.1-second delay at the atrioventricular (AV)
node?
A. It allows the ventricles to finish contracting before the atria begin.
B. It allows the atria to complete their contraction and maximize ventricular filling.
C. It ensures the atria have enough time to fill with blood from the veins.
D. It prevents the SA node from firing too rapidly.
Answer: B
Conceptual Explanation: The AV node delay ensures that atrial systole is completed,
pushing the remaining blood into the ventricles before ventricular systole begins.
4. During which phase of the cardiac cycle are all four heart valves closed and the ventricular
volume remains constant while pressure increases?
A. Ventricular filling
B. Ventricular ejection
C. Isovolumetric contraction
D. Isovolumetric relaxation
, Answer: C
Conceptual Explanation: During isovolumetric contraction, the ventricles contract with
both AV and semilunar valves closed, causing a rapid rise in pressure without a change in
volume.
5. Which of the following vessels carries oxygenated blood from the lungs to the left atrium?
A. Pulmonary arteries
B. Superior vena cava
C. Pulmonary veins
D. Coronary sinus
Answer: C
Conceptual Explanation: Unlike most veins, the pulmonary veins carry oxygen-rich blood
from the lungs back to the left side of the heart.
6. The ‘lub’ sound (S1) of the heart is primarily caused by which event?
A. Closure of the semilunar valves
B. Opening of the atrioventricular valves
C. Blood rushing into the aorta
D. Closure of the atrioventricular valves
Answer: D
