Cardiology: Heart Cycle and Atrial Contraction

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Questions and Answers

What is the point called when the ventricle is fully contracted and almost empty of blood?

End-Diastolic Point

Isovolumic Contraction Point

End-Systolic Point (correct)

Ventricular Filling Point

What is the purpose of placing a catheter in the left ventricle of the heart?

To pace the heart

To measure the pressure and volume changes in a single cardiac cycle (correct)

To inject a dye to visualize the coronary arteries

To visualize the opening and closing of the valves

What is the volume of blood left in the ventricle at the end of systole?

100 milliliters

150 milliliters

50 milliliters (correct)

20 milliliters

What is the period called when the ventricle is filling up with blood?

Ventricular Filling Signup and view all the answers

What happens to the mitral valve when the left ventricular pressure exceeds the left atrial pressure?

It closes Signup and view all the answers

What is the term for the graph that shows the relationship between the left ventricular volume and pressure?

Pressure-Volume Loop Signup and view all the answers

What is the term for the maximum volume of blood in the ventricle?

End-Diastolic Volume (EDV) Signup and view all the answers

What happens to the ventricle when the wave of excitation spreads to it?

It contracts Signup and view all the answers

What is the term for the contraction of the left atrium that pushes the final bit of blood into the left ventricle?

Atrial kick Signup and view all the answers

What happens to the pressure in the left ventricle during the isovolumic contraction phase?

It increases Signup and view all the answers

What is the condition required for the aortic valve to open?

Left ventricular pressure exceeds aortic pressure Signup and view all the answers

What happens to the volume of the left ventricle during the isovolumic contraction phase?

It remains constant Signup and view all the answers

What is the term for the phase of contraction during which the ventricle starts to empty and the pressure is high in it?

Ventricular ejection Signup and view all the answers

What is the main purpose of the atrial kick?

To fill the left ventricle with extra blood Signup and view all the answers

What happens to the left ventricular pressure at Point #7?

It starts to fall Signup and view all the answers

What is the phase of the cardiac cycle when the aortic pressure is falling?

Diastole Signup and view all the answers

What is the term for the electrical excitation that spreads through the left ventricle and causes it to contract?

QRS complex Signup and view all the answers

What is the relationship between the left atrial pressure and the left ventricular pressure during the diastolic phase?

The left atrial pressure is higher than the left ventricular pressure Signup and view all the answers

What is the condition required for the ventricle to start emptying?

Left ventricular pressure exceeds aortic pressure Signup and view all the answers

What happens to the valve during the diastolic phase?

The valve opens Signup and view all the answers

What is the significance of the P wave on the ECG?

It indicates the contraction of the left atrium Signup and view all the answers

What is the volume of the left ventricle during the diastolic phase?

Very high Signup and view all the answers

What is the purpose of the atrial contraction during the cardiac cycle?

To fill the left ventricle with extra blood Signup and view all the answers

What is the phase of the cardiac cycle when the left ventricle is almost full of blood?

Diastole Signup and view all the answers

What is the primary reason for the alteration of the arterial pulse wave at different points in the vascular tree?

The compliance and physical properties of the vascular network Signup and view all the answers

What is the term used to describe the increase in pulse pressure due to the summative interference of the forward and reflected waves?

Augmentation Signup and view all the answers

What is the primary cause of the two primary heart sounds (S1 and S2)?

The closure of the atrioventricular valves Signup and view all the answers

What is the term used to describe the abnormal heart rhythm illustrated in the slide?

Gallop rhythm Signup and view all the answers

What is the frequency of the first heart sound (S1)?

Low frequency Signup and view all the answers

What is the primary function of the atrioventricular valves?

To separate the atria and ventricles Signup and view all the answers

What is the term used to describe the phenomenon where the forward and reflected waves are out of phase?

Interference Signup and view all the answers

What is the primary factor that determines the shape of the arterial pulse wave at different points in the vascular tree?

The physical properties of the vascular network Signup and view all the answers

What is the primary purpose of measuring pressures and volumes in the heart?

To derive pressure-volume loops that provide information about cardiac function Signup and view all the answers

What is the significance of the jugular venous pulse in cardiac function?

It provides information about cardiac function and the circulation Signup and view all the answers

What is the relationship between the electrical events of the ECG and the timing of pressure and volume changes within the heart?

The electrical events of the ECG occur before the pressure and volume changes Signup and view all the answers

What is the underlying cause of the systolic murmur associated with mitral incompetence?

Abnormalities in the mitral valve Signup and view all the answers

How do the peripheral arterial pulse changes affect cardiac function?

The changes in the peripheral arterial pulse are dependent on age and the presence of atherosclerosis Signup and view all the answers

What is the primary purpose of understanding the hydrostatic effects on venous and arterial blood pressure?

To assess cardiac function and circulation Signup and view all the answers

Study Notes

Cardiac Cycle

The cardiac cycle consists of two main phases: Diastole (the gap between beats) and Systole (the contractile phase).
During Diastole, the left atrial pressure is higher than the left ventricular pressure, causing the valve to open and blood to flow from the left atrium into the left ventricle.
At Point #1, the left atrium contracts, pushing the final bit of blood into the left ventricle, known as the atrial kick.

Atrial Contraction

At Point #2, the left atrium contracts, causing the atrial kick.
The atrial kick gives a little extra filling of the left ventricle as the final bit of blood is pushed into it.

Ventricular Contraction

At Point #3, the electrical excitation (QRS complex) occurs, causing the left ventricle to contract.
The contraction raises the pressure in the left ventricle, and the pressure starts to rise very steeply.
At Point #4, the ventricle is in the isovolumic contraction phase, where the pressure rises, but the volume doesn't change.

Ventricular Ejection

At Point #5, the left ventricular pressure exceeds the aortic pressure, causing the aortic valve to open.
The ventricle starts to empty, and the pressure is high, pushing blood out through the aortic valve.
This phase is called ventricular ejection.

Pressure-Volume Loop

A pressure-volume loop can be generated by measuring the pressure and volume changes in a single cardiac cycle.
The loop shows the relationship between left ventricular volume and pressure.
The loop starts at the bottom left corner, where the ventricle is essentially empty, and reaches the End Systolic Point (ESV).
As the heart starts to relax, the ventricle fills, and the volume increases from about 50 ml to 120 ml.
At the end-diastolic volume (EDV), the ventricle is full, and the mitral valve closes.

Compliance and Physical Properties

The compliance and physical properties of the vascular network determine the shape of the arterial pulse at different points in the vascular tree.
Reflected waves can interfere with the forward compression wave, altering the pulse wave.
This can cause the pulse pressure to increase in magnitude, known as augmentation.

Heart Sounds

The two primary heart sounds are S1 and S2, typically described as "Lup" and "Dub".
S1 is the initiation of ventricular systole and is the closure of the atrioventricular valves.
S2 is the closure of the semilunar valves in the outflow tracts.
Additional heart sounds, S3 and S4, are not usually heard.
Abnormal heart sounds can be detected, such as a gallop rhythm or systolic murmur associated with mitral incompetence.

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Description

This quiz covers the heart cycle, including the atrial kick, diastole, and systole phases, and how they affect blood pressure and volume.