HARD QUIZ CARDIAC CYCLE

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Questions and Answers

What is the immediate consequence when left ventricular pressure surpasses left atrial pressure?

The papillary muscles relax, preventing valve closure.

The atria initiate rapid contraction to compensate.

The mitral valve closes due to an adverse pressure gradient. (correct)

The mitral valve opens to allow for maximal passive filling.

During the period between the QRS complex and the rise in aortic pressure, what is the state of the cardiac valves?

The pulmonic valve is open, tricuspid valve is closed.

Only the mitral valve is open which leads to rapid filling.

The aortic valve is open, mitral valve is closed.

Both the aortic and mitral valves are closed. (correct)

What signifies the end of the ventricular diastole process in the cardiac cycle?

The ventricles achieving their maximal filled volume for that cycle. (correct)

Left atrial pressure becomes lower than right atrial pressure which is responsible of the movement of blood.

When left ventricular pressure falls below pulmonary artery pressure.

The point when all four cardiac valves are open for maximal filling.

What event directly leads to the closure of the mitral valve?

Increased pressure in the left ventricle exceeding that in the left atrium. (C) Signup and view all the answers

Which of the following takes place during the isovolumetric contraction phase of the cardiac cycle?

The ventricles are contracting with no change in volume. (B) Signup and view all the answers

What is the primary driver for the opening and closing of all heart valves?

Pressure gradients across the valve (D) Signup and view all the answers

During which phase of the cardiac cycle does the maximal rate of ventricular pressure development (LV dP/dtmax) occur?

Isovolumetric Contraction (B) Signup and view all the answers

Which event immediately precedes the opening of the aortic valve?

Left ventricular pressure exceeding aortic pressure (D) Signup and view all the answers

What is the primary function of the papillary muscles and chordae tendineae during ventricular contraction?

To prevent AV valve leaflets from bulging into the atria (A) Signup and view all the answers

Which phase of the cardiac cycle immediately follows the closure of the aortic valve?

Isovolumetric Relaxation (D) Signup and view all the answers

At a resting heart rate, approximately how much of ventricular filling is attributed to atrial contraction?

10% (C) Signup and view all the answers

What is the correct sequence of phases in the cardiac cycle, starting from the end of ventricular filling?

Isovolumetric Contraction, Ejection, Isovolumetric Relaxation, Passive Filling (B) Signup and view all the answers

Which of the following best describes the relationship between left atrial pressure (LAP) and left ventricular pressure (LVP) during the opening of the mitral valve?

LAP > LVP (D) Signup and view all the answers

What is the primary cause of an S3 heart sound?

Rapid expansion of the ventricle during early, rapid filling phase. (C) Signup and view all the answers

In which physiological situation is an S4 heart sound most likely to be heard?

In individuals with stiff, hypertrophied ventricles. (A) Signup and view all the answers

What does the pulmonary capillary wedge pressure (PCWP) indirectly measure?

Left atrial pressure. (A) Signup and view all the answers

During right-sided cardiac catheterization, how is the pulmonary capillary wedge pressure (PCWP) obtained?

By inflating a balloon in a pulmonary artery branch and measuring pressure distal to the balloon. (D) Signup and view all the answers

What marks the beginning of ventricular systole in the cardiac cycle?

Ventricular depolarization. (A) Signup and view all the answers

What event initiates the start of diastole?

Aortic valve closure. (B) Signup and view all the answers

What causes the isovolumetric increase in ventricular pressure at the start of systole?

Ventricular contraction with both the mitral and aortic valves closed. (C) Signup and view all the answers

When does ventricular filling begin during the cardiac cycle?

After the mitral valve opens during ventricular relaxation. (D) Signup and view all the answers

What does ventricular repolarization initiate within the cardiac cycle?

Ventricular relaxation and reduced pressure generation. (C) Signup and view all the answers

Why is the pressure measured at the tip of the catheter several seconds after balloon inflation in a pulmonary artery branch indicative of left atrial pressure?

The balloon allows the pressure to equilibrate between the pulmonary capillary bed and the left atrium. (A) Signup and view all the answers

During which phase of the cardiac cycle are all heart valves normally closed?

Isovolumetric contraction and relaxation (D) Signup and view all the answers

What is the correct calculation for stroke volume (SV)?

SV = End-diastolic volume (EDV) - End-systolic volume (ESV) (D) Signup and view all the answers

What does ventricular ejection fraction (EF) represent?

The fraction of blood ejected from the ventricle relative to the end-diastolic volume. (D) Signup and view all the answers

When might the stroke volume (SV) NOT equal the volume ejected into the aorta?

When there is retrograde flow into the left atrium (C) Signup and view all the answers

During which phase of the cardiac cycle does atrial filling primarily occur?

During ventricular systole and diastole, except for transient impedance during atrial systole (D) Signup and view all the answers

Compared to the left side of the heart, what is the main difference in right-sided pressures?

Right-sided pressures are generally about half those on the left, especially end-diastolic pressures. (D) Signup and view all the answers

Which of the following is a correct relationship between intracardiac pressures?

Right ventricular end-systolic pressure (RVESP) is approximately equal to pulmonary artery systolic pressure (PASP) (A) Signup and view all the answers

What physiological event causes the first heart sound (S1)?

Closure of the mitral and tricuspid valves, marking the start of isovolumetric contraction (B) Signup and view all the answers

Which event causes the second heart sound (S2)?

Closure of the aortic and pulmonic valves at the start of isovolumetric relaxation (B) Signup and view all the answers

What is the correct sequence of events for heart sounds?

S1 follows the QRS complex while S2 follows the T wave (C) Signup and view all the answers

Study Notes

Cardiac Cycle Lecture Notes

The cardiac cycle encompasses the sequence of events that occur during one heartbeat.
It involves contraction and relaxation of the heart chambers, including valve function and pressure changes.
Learning objectives focus on drawing the cardiac cycle, describing valve function, identifying heart sounds, and understanding pressure-volume loops and pulmonary capillary wedge pressure.
Normal values for LVEDV, LVESV, EF, right and left atrial pressures, pulmonary, and aortic pressures are relevant.

Cardiac Chambers and Valves

Diagrams illustrate heart structures: superior and inferior vena cavae (SVC & IVC), right atrium (RA), right ventricle (RV), left atrium (LA), left ventricle (LV), pulmonary artery (PA), aorta (Ao), tricuspid valve (T), pulmonary valve (P), mitral valve (M), and aortic valve (A).
Key abbreviations are defined for clarity.

Basic Phases of the Cardiac Cycle

Systole encompasses ventricular contraction, beginning when ejection begins and ending when ejection ceases. Relaxation, or diastole, begins when ejection ceases and ventricular filling begins after sufficient relaxation.
The cycle involves different phases like isovolumetric contraction and ejection, defined by changes in ventricular pressure and volume, with important references to heart sounds (S1, S2, S3, S4).

Atrial Systole (Phase 1)

Atrial contraction occurs near the end of ventricular diastole, initiated by atrial depolarization (P wave of ECG), increasing atrial pressure.
This forces additional blood into ventricles, contributing significantly to ventricular filling.

Ventricular Systole (Phases 2-4)

Isovolumetric contraction, the second phase, involves increasing ventricular pressure with both mitral and aortic valves closed while filling volume remains constant.
The ejection phase follows; the aortic valve opens and maximal ejection velocity occurs early in phase 3.
Ventricular repolarization occurs, causing a rapid ejection rate decline (phase 4), and residual volume is the end-systolic volume.

Ventricular Diastole (Phases 5-7)

Isovolumetric relaxation is the initial phase of diastole and involves decreasing ventricular pressure, leading to aortic valve closure. Diastole is then marked by mitral valve opening and passive ventricular filling, beginning at approximately 90 % of total filling.

Pulmonary Capillary Wedge Pressure

A critical measurement, it represents left atrial pressure, which is an indirect measure using catheterization.
A balloon-tipped Swan-Ganz catheter inserted into a pulmonary artery branch stops flow.
Measuring the tip pressure several seconds after balloon inflation provides a left atrial pressure reading.
It's crucial for evaluating heart function.

Intracardiac Pressure Measurements

Diagrams display waveforms of intracardiac pressure changes in different heart chambers and vessels, showing the correlation of pressure with time.
Examples of these graphs are for the right atrium, right ventricle, pulmonary artery and pressure in the presence of an inflated balloon.

Basic Heart Sounds

S1: Closure of mitral and tricuspid valves, occurring after the QRS complex at the start of ventricular contraction.
S2: Closure of aortic and pulmonic valves, following the T wave, starting isovolumetric relaxation.
S3: Highly compliant ventricles (children and adults with dilated ventricles), due to rapid filling of the ventricles.
S4: Ventricular stiffening (older people and those with ventricular hypertrophy), due to atrial contraction forcing blood into a stiffer ventricle.

Analysis of the Cardiac Cycle using Left Ventricular Pressure-Volume Loops

Pressure-volume loops are used to display ventricular function through the cardiac cycle.
Demonstrates relationships between pressure, volume, and time.

Ventricular Stroke Volume and Ejection Fraction (EF)

Stroke volume (SV) is the difference between end-diastolic volume (EDV) and end-systolic volume (ESV).
EF is the percentage of blood ejected from the ventricle relative to EDV and calculated via (EDV -ESV)/EDV.
In a normal case, EF is between 55%-60%, lower in weaker or failing hearts.

Cardiac Cycle Questions and Answers

Specific questions and answers regarding mitral valve closure, phases of the cardiac cycle, and the end of ventricular diastole are included.

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Description

Test your understanding of the cardiac cycle with this quiz that covers key events and pressures involved. Questions range from valve actions to pressure changes during specific phases of the cardiac cycle. Perfect for students studying cardiovascular physiology.