Cardiac Cycle Overview

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Questions and Answers

What percentage of ventricular filling occurs passively during diastole?

60%

90%

80%

70% (correct)

How much of the ventricular filling is attributed to the contraction of the atria during the last third of diastole?

25% (correct)

20%

15%

30%

Which statement correctly describes the process of ventricular filling during diastole?

Ventricular filling is solely reliant on the contraction of the ventricles.

Ventricular filling is more significant in the first third of diastole than the last third.

All ventricular filling occurs actively through atrial contraction.

The majority of ventricular filling occurs passively with some contribution from atrial contraction. (correct)

During which phase does the atria's contraction contribute significantly to ventricular filling?

Last third of diastole Signup and view all the answers

What role does the atrial contraction play in overall ventricular filling?

It plays a minor role compared to passive filling. Signup and view all the answers

What can a murmur due to valve disease indicate?

Abnormal blood flow through a heart valve Signup and view all the answers

Where is a clinician most likely to hear a murmur caused by valve disease?

Directly over the affected valve Signup and view all the answers

What occurs during the first third of diastole?

Rapid filling of the ventricles Signup and view all the answers

What is an example of a vascular sound that can be heard outside the heart?

Bruit over the carotid artery Signup and view all the answers

What is true of blood flow during the middle third of diastole?

Only a small amount of blood flows into the ventricles Signup and view all the answers

Which statement describes diastole effectively?

It consists of rapid ventricular filling followed by reduced filling Signup and view all the answers

Which condition is most likely to cause the audible bruit over the carotid artery?

Atherosclerosis Signup and view all the answers

Which phase of the cardiac cycle has the least blood flow into the ventricles?

Middle third of diastole Signup and view all the answers

What does a murmur specifically suggest about the function of a heart valve?

Inadequate or turbulent blood flow Signup and view all the answers

What is primarily happening in the ventricles during diastole?

They are rapidly filling with blood Signup and view all the answers

What happens to the ventricle if the atria fail to function?

The ventricle can still operate satisfactorily. Signup and view all the answers

Under what condition might the signs of heart failure become noticeable?

When the individual exercises. Signup and view all the answers

Which symptom is commonly associated with heart failure when the atria are not functioning?

Shortness of breath. Signup and view all the answers

What is the primary focus of the second lecture in the cardiovascular physiology series?

Demonstration of the cardiac cycle and mechanical events Signup and view all the answers

What percentage does the ventricle reportedly require for optimal operation without the atria?

75% Signup and view all the answers

Which aspect of heart sounds is emphasized in the lecture objectives?

Normal heart sounds and abnormal added sounds Signup and view all the answers

Which statement best describes the impact of atrial failure on overall heart function?

It has minimal effect unless the person is exercising. Signup and view all the answers

What mechanical event of the cardiac cycle is likely covered in the lecture?

Ventricular filling during diastole Signup and view all the answers

Why are added heart sounds significant in a cardiovascular assessment?

They signify abnormalities that can suggest underlying pathologies. Signup and view all the answers

Which sequence of events is most likely part of the cardiac cycle discussed in the lecture?

Ventricular filling, atrial contraction, ventricular ejection Signup and view all the answers

What does systolic pressure indicate?

The peak pressure during the contraction of the heart Signup and view all the answers

Which statement correctly describes diastolic pressure?

It is the lowest pressure in the arteries during heart relaxation. Signup and view all the answers

How do systolic and diastolic pressures relate during a cardiac cycle?

Systolic pressure occurs during heart contraction, while diastolic pressure occurs during relaxation. Signup and view all the answers

In what phase of the cardiac cycle is the systolic pressure measured?

At the peak of ventricular contraction Signup and view all the answers

Which of the following is true about arterial pressure measurements?

Systolic pressure corresponds to the contraction phase of the heart. Signup and view all the answers

Study Notes

Cardiac Cycle

The cardiac cycle encompasses events from the start of one heartbeat to the next
It involves a period of relaxation (diastole) followed by contraction (systole)
Electrical activity triggers muscle contraction, lasting ~50ms after repolarization

Mechanical Events of the Cardiac Cycle

Occurs in distinct phases in the left ventricle:
- Phase I (Filling): Atrial pressure pushes open AV valves, causing rapid ventricular filling
- Phase II (Isovolumetric Contraction): Ventricular pressure rises, closing AV valves, but no volume change
- Phase III (Ejection): Ventricular pressure exceeds aortic pressure, opening semilunar valves, and blood ejects
- Phase IV (Isovolumetric Relaxation): Ventricular pressure drops below aortic pressure, closing semilunar valves, and no volume change

Ventricular Filling

Phase I primarily involves rapid filling due to atrial pressure
The middle third of diastole involves slower ventricular filling
The final third involves atrial contraction, adding ~25% of filling

Important Cardiac Cycle Values

End Diastolic Volume (EDV): Blood volume in ventricles at end of diastole (approximately 110-120ml)
End Systolic Volume (ESV): Blood volume in ventricles at end of systole (approximately 50-60ml)
Stroke Volume (SV): Blood volume ejected per contraction (approximately 70-90ml)
Ejection Fraction (EF): Percentage of EDV that is ejected (approximately 65% for left ventricle and 45% for right ventricle)

Heart Sounds

First Heart Sound (S1): Closure of AV valves (lub)
Second Heart Sound (S2): Closure of semilunar valves (dub)

Abnormal Sounds (Murmurs and Bruits)

Abnormal heart sounds can indicate valve problems or other cardiovascular issues
The resulting turbulent blood flow produces abnormal sounds that can be detected using a stethoscope

Other Relevant Concepts

Cardiac Output (CO): The volume of blood pumped per minute (heart rate x stroke volume)
The rate at which the heart beats affects the duration of the systole and diastole phases. A faster heart rate shortens the time available for ventricular filling

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Description

This quiz covers the cardiac cycle, detailing the events from one heartbeat to the next, including phases of relaxation and contraction. Explore the mechanical events in the left ventricle and understand the phases of ventricular filling, isovolumetric contraction, ejection, and relaxation.