Dr Gawad Physiology Course Online Exam - CVS – Course Lecture 3 – Cardiac Cycle
18 MCQs (Only one correct answer)
Each MCQ: 1 mark, Total mark: 18 (you will get your result immediately by the web)
No Allowed time: Open exam
Good Luck
dr Mohammed Abel Gawad
- 1.
When the heart rate is increased :
- A.
The duration of the cardiac action potential is unchanged.
- B.
The ratio of systole to diastole is unchanged.
- C.
The duration of systole is unchanged.
- D.
The duration of diastole is unchanged.
- E.
None of the above.
Correct Answer
E. None of the above.Explanation
When the heart rate is increased, the duration of the cardiac action potential is actually shortened. This is because the action potential needs to be shorter in order to allow the heart to contract and relax more rapidly. Additionally, the ratio of systole to diastole is also changed when the heart rate increases. As the heart rate increases, the duration of systole decreases and the duration of diastole increases. Therefore, the correct answer is "None of the above" as all the statements are incorrect.Rate this question:
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- 2.
During the maximum ejection phase, all the following is true except:
- A.
The first heart sound is heard
- B.
The ventricular volume is decreased.
- C.
The ventricular pressure is increased
- D.
The aortic pressure is increased.
- E.
It occurs through modified cardiac muscle fibres.
Correct Answer
A. The first heart sound is heardExplanation
During the maximum ejection phase, the ventricular volume is decreased, the ventricular pressure is increased, the aortic pressure is increased, and it occurs through modified cardiac muscle fibers. The first heart sound is not heard during the maximum ejection phase.Rate this question:
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- 3.
Normally, the closure of the A-V valves is initiated when:
- A.
Atria contract.
- B.
Papillary muscles contract.
- C.
Ventricles relax.
- D.
Ventricular pressure exceeds the atrial pressure.
Correct Answer
D. Ventricular pressure exceeds the atrial pressure.Explanation
When the ventricular pressure exceeds the atrial pressure, it indicates that the ventricles have finished filling with blood and are ready to contract. This pressure difference causes the atrioventricular (A-V) valves to close, preventing the backflow of blood from the ventricles into the atria. The closure of the A-V valves is an important step in the cardiac cycle, ensuring that blood is pumped efficiently from the ventricles to the rest of the body. The contraction of the atria and the relaxation of the ventricles are also part of the cardiac cycle but do not directly initiate the closure of the A-V valves.Rate this question:
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- 4.
The first heart sound occurs synchronously with :
- A.
Closure of the semilunar valves.
- B.
Opening of the AV valves.
- C.
rise in atrial pressure.
- D.
Decrease in ventricular pressure.
Correct Answer
C. rise in atrial pressure.Explanation
The first heart sound occurs synchronously with the rise in atrial pressure. This is because the first heart sound, also known as S1, is caused by the closure of the AV valves (mitral and tricuspid valves) during ventricular systole. The rise in atrial pressure is a result of atrial contraction, which occurs just before ventricular systole. As the atria contract, the pressure within them increases, leading to the closure of the AV valves and the production of the first heart sound.Rate this question:
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- 5.
The “a” wave of the J.V.P. is caused by the :
- A.
Pacemaker potential.
- B.
Atrial depolarization.
- C.
Ventricular repolarization.
- D.
Atrial contraction.
Correct Answer
D. Atrial contraction.Explanation
The "a" wave of the J.V.P. is caused by atrial contraction. The J.V.P. (Jugular Venous Pressure) waveform represents the pressure changes in the jugular vein, which is influenced by various events in the cardiac cycle. The "a" wave is typically seen after the "c" wave and corresponds to the contraction of the atria. During atrial contraction, blood is pushed into the ventricles, causing a small rise in jugular venous pressure, which is reflected as the "a" wave on the J.V.P. waveform.Rate this question:
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- 6.
The C wave of J.V.P. occurs :
- A.
At the onset of expiration.
- B.
During the isovolumetric contraction phase of the cardiac cycle.
- C.
Just before the atrial systole.
- D.
Just after the dicrotic notch of the aortic pressure curve.
Correct Answer
B. During the isovolumetric contraction phase of the cardiac cycle.Explanation
During the isovolumetric contraction phase of the cardiac cycle, the ventricles contract and increase their pressure without any change in volume. This phase occurs after the closure of the mitral and tricuspid valves and before the opening of the aortic and pulmonary valves. The C wave of J.V.P. is caused by the contraction of the right ventricle during this phase, leading to a slight increase in the jugular venous pressure.Rate this question:
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- 7.
During “y” wave of JVP, the filling of the Ventricle by about:
- A.
0 - 5%
- B.
20 – 30%
- C.
40 – 60%
- D.
60 – 80%
- E.
100%
Correct Answer
D. 60 – 80%Explanation
During the "y" wave of JVP, the filling of the ventricle is approximately 60-80%. This means that the ventricle is being filled with blood to a moderate extent during this phase. The "y" wave represents the filling of the ventricle after the closure of the tricuspid valve, and it occurs during late diastole. This moderate filling allows for the ventricle to have enough blood to pump effectively during the subsequent systole phase.Rate this question:
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- 8.
The atrial contraction causes the :
- A.
Incisura of the aortic pressure curve.
- B.
“a” wave of the JVP.
- C.
Ascending limb limb of the arterial pulse wave.
- D.
Dicrotic wave of the arterial pulse curve.
Correct Answer
B. “a” wave of the JVP.Explanation
The "a" wave of the JVP is caused by atrial contraction. When the atria contract, it pushes blood into the right ventricle, causing a small increase in pressure in the jugular veins. This increase in pressure creates a small upward deflection on the JVP waveform, known as the "a" wave. The other options mentioned in the question are not directly related to atrial contraction.Rate this question:
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- 9.
During systole, the ventricular ejection of blood is :
- A.
Highest in the first third of ventricular systole
- B.
Highest in the middle third of ventricular systole
- C.
Highest in the last third of ventricular systole
- D.
Roughly equal throughout.
Correct Answer
B. Highest in the middle third of ventricular systoleExplanation
During systole, the ventricular ejection of blood is highest in the middle third of ventricular systole. This is because during this phase, the ventricles contract forcefully, leading to increased pressure in the ventricles and the opening of the semilunar valves. As a result, blood is ejected from the ventricles into the aorta and pulmonary artery. In the first third of ventricular systole, the ventricles are just beginning to contract, and in the last third, the ventricles are starting to relax. Therefore, the middle third is when the ejection of blood is at its highest.Rate this question:
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- 10.
The dicrotic notch (incisura) in the aortic pressure curve is :
- A.
Of no diagnostic value.
- B.
Coincident with increased ventricular pressure than that of the aorta
- C.
Indicative of heart disease.
- D.
Coincident with high atrial pressure
Correct Answer
D. Coincident with high atrial pressureExplanation
The dicrotic notch in the aortic pressure curve is coincident with high atrial pressure. This means that when the atria of the heart contract to push blood into the ventricles, the pressure in the atria increases, causing the dicrotic notch to appear in the aortic pressure curve. This can be an indication of high atrial pressure, which may be caused by various heart diseases or conditions. Therefore, the presence of the dicrotic notch can be indicative of heart disease.Rate this question:
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- 11.
Opening of the aortic valve occurs when the :
- A.
Atria contract.
- B.
Ventricles relax.
- C.
Ventricles contract.
- D.
Ventricular pressure exceeds the aortic pressure.
Correct Answer
D. Ventricular pressure exceeds the aortic pressure.Explanation
The opening of the aortic valve occurs when the ventricular pressure exceeds the aortic pressure. This is because the aortic valve is a one-way valve that allows blood to flow from the left ventricle into the aorta. When the pressure in the ventricles is higher than the pressure in the aorta, the valve opens, allowing blood to be pumped out of the heart and into the systemic circulation. Once the ventricular pressure drops below the aortic pressure, the valve closes to prevent backflow of blood into the ventricles.Rate this question:
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- 12.
During the normal cardiac cycle:
- A.
Ventricular ejection of blood occurs thought all ventricular systole
- B.
The first sound is due to closure of the mitral and aortic valves.
- C.
The atrial systole occurs during ventricular filling i.e. ventricular diastole
- D.
None of the above
Correct Answer
C. The atrial systole occurs during ventricular filling i.e. ventricular diastoleExplanation
During the normal cardiac cycle, the atrial systole occurs during ventricular filling, which is also known as ventricular diastole. This means that while the ventricles are relaxed and filling with blood, the atria contract to push additional blood into the ventricles. This is an important step in the cardiac cycle as it helps to increase the volume of blood in the ventricles before they contract and eject blood out of the heart.Rate this question:
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- 13.
The dicrotic notch on the aortic pressure curve is caused by :
- A.
Decreased ventricular pressure than that of the aorta
- B.
Rapid filling of the left ventricle.
- C.
Opening of the pulmonary valve.
- D.
Elastic recoil of the aorta.
Correct Answer
A. Decreased ventricular pressure than that of the aortaExplanation
The dicrotic notch on the aortic pressure curve is caused by decreased ventricular pressure than that of the aorta. During systole, the left ventricle contracts and pumps blood into the aorta, causing the aortic pressure to rise. However, after systole, the ventricular pressure decreases as the ventricle relaxes. This decrease in ventricular pressure causes the aortic valve to close, resulting in the dicrotic notch on the pressure curve. The rapid filling of the left ventricle, opening of the pulmonary valve, and elastic recoil of the aorta are not directly responsible for the dicrotic notch.Rate this question:
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- 14.
The V wave of the JVP is produced by :
- A.
The atrial systole.
- B.
Rise of the ventricular pressure during the isovolumetric contraction phase.
- C.
Ventricular ejection.
- D.
Rise of the right atrial pressure before the tricuspid valve opens.
- E.
Opening of the semilunar valves.
Correct Answer
D. Rise of the right atrial pressure before the tricuspid valve opens.Explanation
The V wave of the JVP is produced by the rise of the right atrial pressure before the tricuspid valve opens. During this phase, blood is returning to the right atrium from the systemic circulation, causing an increase in pressure within the atrium. This increase in pressure is reflected as the V wave on the JVP waveform.Rate this question:
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- 15.
During “a” wave of JVP, the filling of the Ventricle by about:
- A.
0 - 5%
- B.
20 – 30%
- C.
40 – 60%
- D.
60 – 80%
- E.
100%
Correct Answer
B. 20 – 30%Explanation
During the "a" wave of JVP, the filling of the ventricle occurs to about 20-30%. This means that during this phase, the ventricle is only partially filled with blood, as opposed to being completely filled (100%). The "a" wave of JVP represents the contraction of the atria, which pushes blood into the ventricle. This partial filling allows for efficient filling and subsequent ejection of blood from the ventricle during the cardiac cycle.Rate this question:
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- 16.
At which phase of cardiac cycle are all valves closed:
- A.
Atrial systole.
- B.
Isometric phase of contraction
- C.
Ejection phase.
- D.
Filling phase.
Correct Answer
B. Isometric phase of contractionExplanation
During the isometric phase of contraction, all valves in the heart are closed. This phase occurs after the atria have contracted and before the ventricles start to contract. The closure of all valves during this phase is important to prevent the backflow of blood and to build up pressure within the ventricles. Once the pressure within the ventricles exceeds the pressure in the arteries, the valves will open and blood will be ejected into the arteries during the ejection phase. Therefore, the correct answer is the isometric phase of contraction.Rate this question:
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- 17.
During the isovolumetric contraction phase of the cardiac cycle:
- A.
The ventricular pressure is decreased
- B.
The ventricular volume is increased.
- C.
The coronary blood flow is decreased.
- D.
The atrial pressure is unchanged.
- E.
No heart sounds are heard
Correct Answer
C. The coronary blood flow is decreased.Explanation
During the isovolumetric contraction phase of the cardiac cycle, the ventricles are contracting but the ventricular volume remains constant. This means that the blood is not being pumped out of the ventricles yet, and as a result, the coronary blood flow is decreased. The decrease in coronary blood flow during this phase is due to the fact that the coronary arteries are compressed by the contracting ventricles, limiting the amount of blood that can flow through them.Rate this question:
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- 18.
During the isovolumetric contraction phase of the cardiac cycle:
- A.
All valves of the heart are open.
- B.
There is no change in the tension of ventricular muscle.
- C.
There is no energy expenditure.
- D.
There is a parallel change in both the ventricular and aortic pressures i.e. both increased
- E.
There is no external work done.
Correct Answer
E. There is no external work done.Explanation
During the isovolumetric contraction phase of the cardiac cycle, the ventricles contract and increase their pressure, but the valves leading out of the ventricles (aortic and pulmonary valves) remain closed. This means that no blood is being ejected from the ventricles, and therefore no external work is being done. The contraction of the ventricular muscles during this phase is isometric, meaning there is no change in muscle length and no change in tension. However, internal work is still being done as the ventricles build up pressure to overcome the resistance of the closed valves.Rate this question:
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Mar 21, 2023Quiz Edited by
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Mar 24, 2017Quiz Created by
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