Cardiac Cycle Overview

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Questions and Answers

What does the end diastolic ventricular volume represent?

The percentage of the ventricular volume ejected with each stroke.

The volume of blood that remains in the ventricle at the end of systole.

The volume of blood in each ventricle at the end of diastole. (correct)

The amount of blood ejected by each ventricle per stroke.

Which of the following is a normal value for ejection fraction?

50 to 60%

45 to 55%

70 to 80%

55 to 65% (correct)

What produces the first heart sound during the cardiac cycle?

Rapid filling of the ventricles.

Closure of the AV valves. (correct)

Vibrations from myocardial contraction.

Closure of the semilunar valves.

What indicates good ventricular function in a cardiac cycle?

Normal ejection fraction. Signup and view all the answers

When does the second heart sound occur in the cardiac cycle?

At the end of ventricular systole. Signup and view all the answers

Which heart sound is typically inaudible in adults?

Fourth heart sound. Signup and view all the answers

What is the stroke volume range during resting conditions?

70 - 90 ml Signup and view all the answers

Which factor can cause the third heart sound to be pathological?

Rushing of blood from atria to ventricle. Signup and view all the answers

What characterizes valvular stenosis?

Narrowing of the valve Signup and view all the answers

What is a common result of aortic stenosis?

Increased left ventricular systolic pressure Signup and view all the answers

What occurs during a diastolic murmur of mitral stenosis?

Pressure and volume in the left atrium are increased Signup and view all the answers

What is the effect of heart failure on ventricular pressure?

Fall in ventricular systolic pressure Signup and view all the answers

During aortic regurgitation, which physiological change occurs?

Increased preload Signup and view all the answers

What is a characteristic of systolic murmur in mitral regurgitation?

There is no pressure gradient between atrium and ventricle Signup and view all the answers

What effect does heavy exercise have on preload?

Preload increases significantly Signup and view all the answers

Which of the following correctly describes a characteristic of a diastolic murmur?

It results from abnormal backward flow of blood Signup and view all the answers

Study Notes

Cardiac Cycle

Cardiac cycle is the sequence of events that occurs in the heart during a single heartbeat.
Pressure-volume loop is a graphical representation of the pressure and volume changes that occur in the left ventricle during a cardiac cycle.
End diastolic ventricular volume (EDV) is the volume of blood in the left ventricle at the end of diastole (130 ml).
End systolic ventricular volume (ESV) is the volume of blood remaining in the left ventricle at the end of systole (50 ml).
Stroke volume (SV) is the amount of blood ejected by the left ventricle per beat (70-90 ml).
Ejection fraction (EF) is the percentage of the ventricular volume ejected with each heartbeat (55-65%).
Heart sounds are produced by vibrations caused by the sudden closure of heart valves or by myocardial contraction.
First heart sound (S1) is caused by the closure of the AV valves (mitral and tricuspid) at the beginning of ventricular systole.
- Low-pitched (25-45 Hz)
- Longer duration (0.14 sec)
Second heart sound (S2) is caused by closure of the semilunar valves (aortic and pulmonary) at the end of ventricular systole.
- High-pitched (50 Hz)
- Shorter duration (0.11 sec)
Third heart sound (S3) is caused by the rapid flow of blood from the atria into the ventricle during the rapid filling phase of diastole.
- Normal in children and young adults.
- May be pathological, indicating heart failure.
Fourth heart sound (S4) is caused by atrial contraction at the end of ventricular diastole.
- Normally inaudible.
- Indicates resistance to ventricular filling.
Cardiac murmurs are abnormal heart sounds that occur in valvular diseases and septal defects.
- Occur during the closure of valves and are audible with a stethoscope.

Valvular Diseases

Valvular stenosis is the narrowing of a heart valve, restricting blood flow.
Valvular insufficiency (incompetence) is the inability of a heart valve to close fully, leading to backflow (regurgitation) of blood.

Types of Murmurs

Systolic murmur occurs during ventricular contraction (systole).
Diastolic murmur occurs during ventricular relaxation (diastole).

Aortic Stenosis

Blood is ejected from the left ventricle through a narrowed aortic valve, increasing systolic pressure.
Features:
- Systolic murmur
- Concentric hypertrophy

Aortic Regurgitation

Backflow of blood from the aorta into the left ventricle during diastole.
Features:
- Diastolic murmur
- Increased end-diastolic volume (EDV)
- Eccentric hypertrophy

Mitral Stenosis

Blood struggles to pass through the narrowed mitral valve, impairing the emptying of the left atrium into the ventricle.
Features:
- Diastolic murmur
- Increased left atrial pressure and volume.

Mitral Regurgitation

Backflow of blood from the left ventricle into the left atrium during ventricular systole.
Features:
- Systolic murmur
- Increased atrial pressure and volume
- Increased ventricular volume and pressure during diastole.

Altered States and Changes in Pressure and Volume

Exercise:
- Increased ventricular pressure
- Increased preload only during heavy exercise
- Decreased ESV due to increased EF.
Heart failure:
- Decreased ventricular systolic pressure
- Increased preload
- Rightward shift of the pressure-volume loop
Aortic stenosis:
- Increased left ventricular systolic pressure
Aortic insufficiency:
- Increased preload
- Increased left ventricular pressure

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Description

This quiz covers the cardiac cycle, focusing on key concepts such as pressure-volume loops, stroke volume, and ejection fraction. Test your understanding of the heart's functioning during one complete heartbeat, including important terms and definitions that are essential for grasping cardiac physiology.