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Questions and Answers
What happens to the atrial pressure during the reduced ejection phase?
What happens to the atrial pressure during the reduced ejection phase?
By what percentage does the ventricular volume decrease during the reduced ejection phase?
By what percentage does the ventricular volume decrease during the reduced ejection phase?
What is the end systolic volume (ESV) at the end of the reduced ejection phase?
What is the end systolic volume (ESV) at the end of the reduced ejection phase?
What happens to the semilunar and A-V valves during the reduced ejection phase?
What happens to the semilunar and A-V valves during the reduced ejection phase?
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What is observed on the ECG during the reduced ejection phase?
What is observed on the ECG during the reduced ejection phase?
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What is the primary function of diastole in the cardiac cycle?
What is the primary function of diastole in the cardiac cycle?
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At a heart rate of 75 bpm, what is the duration of the cardiac cycle?
At a heart rate of 75 bpm, what is the duration of the cardiac cycle?
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Which phase occupies a greater proportion of the cardiac cycle duration?
Which phase occupies a greater proportion of the cardiac cycle duration?
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What happens to the duration of the cardiac cycle at higher heart rates?
What happens to the duration of the cardiac cycle at higher heart rates?
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What is the ejection phase of the cardiac cycle associated with?
What is the ejection phase of the cardiac cycle associated with?
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What proportion of the cardiac cycle does diastole occupy at a heart rate of 200 bpm?
What proportion of the cardiac cycle does diastole occupy at a heart rate of 200 bpm?
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Which part of the heart acts as a pressure pump during the cardiac cycle?
Which part of the heart acts as a pressure pump during the cardiac cycle?
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How does the atrial systole contribute to filling the ventricles?
How does the atrial systole contribute to filling the ventricles?
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What percentage of ventricular filling is attributed to atrial systole?
What percentage of ventricular filling is attributed to atrial systole?
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Which phase of the cardiac cycle occurs immediately after atrial systole?
Which phase of the cardiac cycle occurs immediately after atrial systole?
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During atrial systole, what happens to the ventricular volume?
During atrial systole, what happens to the ventricular volume?
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What does atrial systole primarily cause in the atrial pressure curve?
What does atrial systole primarily cause in the atrial pressure curve?
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What occurs to the aortic pressure during atrial systole?
What occurs to the aortic pressure during atrial systole?
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Which heart sound is primarily associated with atrial systole?
Which heart sound is primarily associated with atrial systole?
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What role does atrial systole play when the heart rate increases?
What role does atrial systole play when the heart rate increases?
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What is the duration of the atrial systole phase?
What is the duration of the atrial systole phase?
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What characterizes the isovolumetric contraction phase during ventricular systole?
What characterizes the isovolumetric contraction phase during ventricular systole?
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During the isovolumetric contraction phase, which of the following is true about ventricular volume?
During the isovolumetric contraction phase, which of the following is true about ventricular volume?
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What happens to ventricular pressure during isovolumetric contraction?
What happens to ventricular pressure during isovolumetric contraction?
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Which event occurs immediately after the closure of the A-V valves?
Which event occurs immediately after the closure of the A-V valves?
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What effect does the isovolumetric contraction phase have on atrial pressure?
What effect does the isovolumetric contraction phase have on atrial pressure?
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What distinguishes the end of the isovolumetric contraction phase?
What distinguishes the end of the isovolumetric contraction phase?
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During isovolumetric contraction, what happens to aortic pressure?
During isovolumetric contraction, what happens to aortic pressure?
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What is the primary characteristic of the ventricles during isovolumetric contraction?
What is the primary characteristic of the ventricles during isovolumetric contraction?
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What is the cardiac cycle primarily defined as?
What is the cardiac cycle primarily defined as?
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What occurs during systole in the cardiac cycle?
What occurs during systole in the cardiac cycle?
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Which event change is typical during diastole?
Which event change is typical during diastole?
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What effect does tachycardia have on the cardiac cycle?
What effect does tachycardia have on the cardiac cycle?
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How is the blood flow affected during the cardiac cycle?
How is the blood flow affected during the cardiac cycle?
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What is the primary role of the heart valves during the cardiac cycle?
What is the primary role of the heart valves during the cardiac cycle?
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Which chambers of the heart undergo simultaneous changes during the cardiac cycle?
Which chambers of the heart undergo simultaneous changes during the cardiac cycle?
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What significant changes occur in the heart during each phase of the cardiac cycle?
What significant changes occur in the heart during each phase of the cardiac cycle?
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What initiates the first heart sound (S1)?
What initiates the first heart sound (S1)?
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During which phase is the ventricular volume markedly decreased?
During which phase is the ventricular volume markedly decreased?
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What is the highest systolic blood pressure (SBP) in the left ventricle during the Rapid Ejection Phase?
What is the highest systolic blood pressure (SBP) in the left ventricle during the Rapid Ejection Phase?
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Which valves are closed during the Rapid Ejection Phase?
Which valves are closed during the Rapid Ejection Phase?
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What significant wave begins just before the Rapid Ejection Phase?
What significant wave begins just before the Rapid Ejection Phase?
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What happens to the aortic pressure during the Rapid Ejection Phase?
What happens to the aortic pressure during the Rapid Ejection Phase?
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Which heart sound is still heard during the Rapid Ejection Phase?
Which heart sound is still heard during the Rapid Ejection Phase?
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Study Notes
Cardiac Cycle Overview
- The cardiac cycle is the mechanical response of the heart in one beat.
- It's a sequence of events resulting from electrical activation.
- The cycle involves volume and pressure changes in heart chambers and connected arteries/veins.
- The heart's valves change position (open/closed) in a coordinated manner.
- Systole is the contraction phase, and diastole is the relaxation phase.
- Systole's function is ejection; emptying the ventricles into arteries.
- Diastole's function is filling; filling the ventricles from atria and veins.
Cardiac Cycle Phases
- The cardiac cycle has 8 phases.
- Atrial systole: The atria contract, aiding ventricle filling.
- Isovolumetric contraction: All valves closed, ventricular pressure rises.
- Rapid ejection: Semilunar valves open, blood exits ventricles.
- Reduced ejection: Ventricular pressure decreases, less blood leaves.
- Protodiastole: Initial relaxation phase.
- Isovolumetric relaxation: All valves are closed, ventricular pressure decreases.
- Rapid filling: Ventricles fill rapidly.
- Reduced filling: Very slow ventricular filling.
Effects of Tachycardia
- Increased heart rate shortens cardiac cycle duration, mostly affecting diastole.
Changes in Each Phase
- Atrial pressure: Increases during atrial systole.
- Ventricular volume: Increases during diastole, decreases during systole.
- Ventricular pressure: Increases during systole.
- Aortic pressure: Increases during systole.
- Heart valves: Open and close in a specific sequence.
- Heart sounds (S1 and S2): Correspond to valve closures.
- ECG (Electrocardiogram): Specific waveforms correspond to heart activity.
1-Atrial Systole
- Occurs in the first phase of a new cycle.
- While ventricles still in the last diastole phase.
- Completed before the ventricles start contraction.
- Important for about 20-30% of ventricular filling.
- Increasing role with higher heart rates.
- Represents assistance in ventricular filling.
Ventricular Systole
- Has 3 phases:
- Isovolumetric contraction: All valves closed, ventricular pressure rise.
- Rapid ejection: Semilunar valves open, forceful blood ejection.
- Reduced ejection: Decreasing ventricular pressure and blood ejection.
Isovolumetric Contraction
- Ventricles contract as closed chambers (isometric).
- Maximizes ventricular wall tension, causing pressure rise.
- Switches ventricular pressure from low to high-pressure system.
Isometric Contraction Phase Events
- Atrial pressure increases slightly due to valve bulging.
- Ventricular volume stays the same.
- Ventricular pressure increases rapidly towards aortic and pulmonary pressures.
- Aortic pressure decreases while semilunar valves still closed.
- All valves remain closed during this phase.
- The first heart sound (S1) occurs as all valves close.
- ECG shows the Q wave before and QRS complex during this phase.
2- Rapid Ejection Phase
- Ejection is the proper function of systole.
- Both semilunar valves open in this phase.
- Most blood ejection (~70%) into aorta and pulmonary artery.
3- Reduced Ejection Phase
- Continuation of the rapid ejection phase.
- Blood continues to leave the ventricle, going into the aorta and pulmonary arteries.
Events during Reduced Ejection Phase
- Atrial pressure gradually increases due to venous return.
- Ventricle volume decreases with slower blood ejection.
- Ventricular pressure decreases until it is below aortic pressure.
- Aortic pressure starts decreasing due to outflow to the periphery.
- All valves (AV and semilunar) still in same position (AV closed, semilunar open).
- ECG first half and top of T wave.
Duration of the Cardiac Cycle
- 0.8 seconds at a heart rate of 75 bpm.
- Diastole lasts about 2/3 of the cycle (0.53 sec).
- Systole lasts about 1/3 of the cycle (0.27 sec).
- Cardiac cycle duration decreases with increased heart rate.
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Description
This quiz covers the essential aspects of the cardiac cycle, including its mechanical responses, phases, and the role of systole and diastole. You will explore the 8 phases of the cardiac cycle, focusing on how the heart's chambers and valves function during each stage. Test your knowledge on how electrical activation leads to these mechanical events.
