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Questions and Answers
Which node initiates each cardiac cycle?
Which node initiates each cardiac cycle?
What is the duration of systole in relation to the total duration of the cardiac cycle?
What is the duration of systole in relation to the total duration of the cardiac cycle?
What happens during systole?
What happens during systole?
What is the duration of diastole in relation to the total duration of the cardiac cycle?
What is the duration of diastole in relation to the total duration of the cardiac cycle?
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What happens during diastole?
What happens during diastole?
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What is directly affected when heart rate increases?
What is directly affected when heart rate increases?
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What is the volume of blood remaining in the ventricle at the end of ejection called?
What is the volume of blood remaining in the ventricle at the end of ejection called?
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What is the equation for stroke volume (SV)?
What is the equation for stroke volume (SV)?
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What is the equation for cardiac output (CO)?
What is the equation for cardiac output (CO)?
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What is the ejection fraction (EF)?
What is the ejection fraction (EF)?
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Which side of the heart has pressures that are approximately one-fourth to one-fifth of the other side?
Which side of the heart has pressures that are approximately one-fourth to one-fifth of the other side?
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What is the volume of blood pumped by the heart per minute called?
What is the volume of blood pumped by the heart per minute called?
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Which equation represents the length of the cardiac cycle?
Which equation represents the length of the cardiac cycle?
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What is the term for the volume of blood ejected from the ventricle?
What is the term for the volume of blood ejected from the ventricle?
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Which fraction is used to calculate the ejection fraction?
Which fraction is used to calculate the ejection fraction?
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What does the ejection fraction (EF) measure?
What does the ejection fraction (EF) measure?
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During isovolumic contraction, the volume of the left ventricle
During isovolumic contraction, the volume of the left ventricle
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What happens at the start of ejection?
What happens at the start of ejection?
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What is the ejection fraction (EF) a measure of?
What is the ejection fraction (EF) a measure of?
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What is the equation for ejection fraction (EF)?
What is the equation for ejection fraction (EF)?
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What happens at the end of isovolumic contraction?
What happens at the end of isovolumic contraction?
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What is the pressure within the left ventricle at the start of ejection?
What is the pressure within the left ventricle at the start of ejection?
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What is the stroke volume (SV)?
What is the stroke volume (SV)?
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What happens when the aortic valve closes?
What happens when the aortic valve closes?
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What happens during isovolumic relaxation?
What happens during isovolumic relaxation?
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What is the pressure within the left ventricle at the start of ejection?
What is the pressure within the left ventricle at the start of ejection?
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What happens during diastole?
What happens during diastole?
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What is the volume of blood that fills the ventricle during atrial contraction?
What is the volume of blood that fills the ventricle during atrial contraction?
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What is the term for the volume of blood ejected from the ventricle?
What is the term for the volume of blood ejected from the ventricle?
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What is the equation for cardiac output (CO)?
What is the equation for cardiac output (CO)?
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Which wave is caused by filling of the atria during ventricular systole?
Which wave is caused by filling of the atria during ventricular systole?
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What happens if an abnormal opening exists between the right heart and the left heart?
What happens if an abnormal opening exists between the right heart and the left heart?
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What is the function of the cardiac valves?
What is the function of the cardiac valves?
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How do the cardiac valve leaflets move?
How do the cardiac valve leaflets move?
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When do the valves open?
When do the valves open?
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What causes the leaflets of the valves to begin closing?
What causes the leaflets of the valves to begin closing?
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What causes the final closing motions of the valves?
What causes the final closing motions of the valves?
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What supports the atrioventricular valves when closed?
What supports the atrioventricular valves when closed?
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How much blood can normal valves allow to flow in the retrograde direction?
How much blood can normal valves allow to flow in the retrograde direction?
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What happens when the valves are damaged or malformed?
What happens when the valves are damaged or malformed?
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Which wave is produced by the contraction of the atrium?
Which wave is produced by the contraction of the atrium?
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What causes the ‘c’ wave?
What causes the ‘c’ wave?
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Which sound marks the start of systole?
Which sound marks the start of systole?
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What causes the second heart sound (S2)?
What causes the second heart sound (S2)?
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Which component of the second heart sound is associated with aortic valve closure?
Which component of the second heart sound is associated with aortic valve closure?
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What happens to the A2-P2 interval during inspiration?
What happens to the A2-P2 interval during inspiration?
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What is valvular stenosis?
What is valvular stenosis?
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What is valvular insufficiency (regurgitation)?
What is valvular insufficiency (regurgitation)?
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What can cause a murmur in valvular stenosis?
What can cause a murmur in valvular stenosis?
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What can cause a murmur in valvular insufficiency (regurgitation)?
What can cause a murmur in valvular insufficiency (regurgitation)?
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What is the interval between A2 and P2 called?
What is the interval between A2 and P2 called?
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Which sound of the second heart sound occurs first?
Which sound of the second heart sound occurs first?
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Which sound marks the end of systole?
Which sound marks the end of systole?
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What causes the first heart sound (S1)?
What causes the first heart sound (S1)?
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Which component of the second heart sound (S2) is associated with pulmonic valve closure?
Which component of the second heart sound (S2) is associated with pulmonic valve closure?
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Study Notes
Cardiac Cycle
- The sinoatrial (SA) node initiates each cardiac cycle
- Systole lasts for approximately 1/3 of the total duration of the cardiac cycle
- During systole, the ventricles contract, pumping blood out of the heart
- Diastole lasts for approximately 2/3 of the total duration of the cardiac cycle
- During diastole, the ventricles relax and fill with blood
Heart Rate and Stroke Volume
- When heart rate increases, the ejection fraction (EF) is directly affected
- The volume of blood remaining in the ventricle at the end of ejection is called the end-systolic volume (ESV)
- The equation for stroke volume (SV) is SV = EDV - ESV
- The equation for cardiac output (CO) is CO = SV x HR
Ejection Fraction and Cardiac Output
- Ejection fraction (EF) is the fraction of blood ejected from the ventricle with each beat
- EF is calculated using the equation EF = (SV / EDV) x 100
- EF measures the heart's pumping efficiency
- The left side of the heart has pressures that are approximately 4-5 times that of the right side
Cardiac Cycle Phases
- Isovolumic contraction occurs when the ventricle contracts without pumping blood out of the heart
- At the start of ejection, the pressure within the left ventricle exceeds the pressure in the aorta, causing the aortic valve to open
- At the end of isovolumic contraction, the aortic valve opens, and ejection begins
- During isovolumic relaxation, the ventricle relaxes without filling with blood
- The atrioventricular valves are supported by the chordae tendineae when closed
Valves and Blood Flow
- The cardiac valves prevent backflow of blood and ensure it flows in one direction
- The valve leaflets move passively in response to pressure changes
- The valves open when the pressure in the chamber exceeds the pressure on the other side of the valve
- The valves close when the pressure on the other side of the valve exceeds the pressure in the chamber
- Normal valves allow a small amount of backflow, but damaged or malformed valves can cause significant backflow
Heart Sounds and Valvular Problems
- The 'c' wave is produced by the contraction of the atrium
- The second heart sound (S2) is caused by the closure of the aortic and pulmonic valves
- The A2 component of the second heart sound is associated with aortic valve closure
- The P2 component of the second heart sound is associated with pulmonic valve closure
- Valvular stenosis is the narrowing of a valve, and valvular insufficiency (regurgitation) is the failure of a valve to close properly
- Murmurs can occur due to valvular stenosis or insufficiency
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Description
Test your knowledge of the cardiac cycle and its two main phases, systole and diastole. Learn about the duration of each phase and how they contribute to the overall heart rate.