The Cardiac Cycle and Heart Sounds

Flashcards summarizing key vocabulary related to the cardiac cycle and heart sounds.

Cardiac Cycle

The sequence of events in the heart that occurs during one heartbeat, involving contraction and relaxation phases.

Diastole

The phase of the cardiac cycle during which the heart muscle relaxes and chambers fill with blood.

Systole

The phase of the cardiac cycle during which the heart muscle contracts and pumps blood out of the chambers.

Mitral Valve (MV)

A valve in the heart that separates the left atrium from the left ventricle.

Tricuspid Valve (TV)

A valve in the heart that separates the right atrium from the right ventricle.

Aortic Valve (AOV)

A valve that opens to allow blood to leave the left ventricle and enter the aorta.

Pulmonic Valve (PV)

A valve that opens to allow blood to leave the right ventricle and enter the pulmonary artery.

Heart Sounds

Sounds produced by the closure of heart valves during the cardiac cycle, primarily the sounds S1 and S2.

S1

The first heart sound, produced by the closure of the mitral and tricuspid valves.

S2

The second heart sound, produced by the closure of the aortic and pulmonic valves.

Physiologic Splitting

A variation in heart sounds where A2 and P2 can be heard as two distinct sounds during inspiration, merging during expiration.

Systolic Murmur

A heart murmur occurring during systole, often resulting from conditions such as aortic stenosis or mitral regurgitation.

Diastolic Murmur

A heart murmur occurring during diastole, typically caused by valve stenosis or regurgitation.

Ejection Click

An extra heart sound heard during systolic ejection, often indicating valve stenosis or chamber dilation.

Continuous Murmur

A type of heart murmur that persists throughout both systole and diastole.

Wigger's Diagram

A graphical representation showing the pressure changes in the heart chambers during the cardiac cycle.

Jugular Venous Pulsations

Visible pulsations in the jugular vein that reflect right atrial pressure.

Atrial Kick

The contribution of the atrial contraction to the ventricular filling during late diastole.

Regurgitant Flow

Backflow of blood caused by the incompetence of heart valves, leading to abnormal murmurs.

Ventricular Gallop (S3)

An abnormal heart sound during rapid ventricular filling, indicating heart failure.

Atrial Gallop (S4)

An abnormal heart sound that occurs in late diastole, often associated with decreased ventricular compliance.

Left Atrium

A chamber of the heart that receives oxygenated blood from the pulmonary veins.

Right Atrium

A chamber of the heart that receives deoxygenated blood from the vena cava.

Left Ventricle

A strong chamber of the heart that pumps oxygenated blood into the aorta to the body.

Right Ventricle

A chamber of the heart that pumps deoxygenated blood into the pulmonary artery to the lungs.

Aorta

The largest artery in the body, which carries oxygenated blood from the left ventricle to the systemic circulation.

Pulmonary Artery

The artery that carries deoxygenated blood from the right ventricle to the lungs.

Sinoatrial (SA) Node

The natural pacemaker of the heart, located in the right atrium, which initiates the electrical impulses for contraction.

Atrioventricular (AV) Node

A part of the cardiac conduction system that delays electrical impulses from the atria before they pass to the ventricles.

Cardiac Output

The volume of blood pumped by the heart per minute, calculated as heart rate multiplied by stroke volume.

Stroke Volume (SV)

The volume of blood pumped out by the left ventricle with each heartbeat.

Preload

The end-diastolic volume that stretches the right or left ventricle, reflecting the amount of blood in the ventricles before contraction.

Afterload

The resistance against which the ventricles must pump blood, primarily influenced by systemic vascular resistance and aortic pressure.

Ejection Fraction (EF)

The percentage of blood pumped out of the ventricle with each beat, calculated as $(\text{Stroke Volume} / \text{End-Diastolic Volume}) \times 100\%$. It is a key indicator of cardiac pump function.

Frank-Starling Law of the Heart

States that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end-diastolic volume) when all other factors remain constant.

Isovolumic Contraction

A brief phase early in ventricular systole where the ventricles contract but there is no change in blood volume as all valves are closed, leading to a rapid increase in intraventricular pressure.

Rapid Ejection

The initial phase of ventricular systole following isovolumic contraction, where the semilunar valves open due to high ventricular pressure, and a large volume of blood is quickly expelled from the ventricles.

Reduced Ejection (Protodiastole)

The later phase of ventricular systole in which ventricular ejection continues at a slower rate as ventricular pressure falls below aortic/pulmonary artery pressure, but still above atrial pressure.

Isovolumic Relaxation

A brief phase at the beginning of ventricular diastole where the ventricles relax and ventricular pressure decreases, but no blood enters or leaves as all valves are closed.

Rapid Ventricular Filling

The initial phase of ventricular diastole following isovolumic relaxation, where the AV valves open and blood flows rapidly from the atria into the ventricles due to pressure gradients.

Reduced Ventricular Filling (Diastasis)

The slower phase of ventricular filling that follows rapid filling, as the pressure gradient between the atria and ventricles decreases and blood flow slows down until atrial contraction.

Blood Flow Pathway (Deoxygenated)

Deoxygenated blood enters the heart via the vena cava, flows into the right atrium, through the tricuspid valve to the right ventricle, and then through the pulmonic valve into the pulmonary artery to the lungs.

Blood Flow Pathway (Oxygenated)

Oxygenated blood returns from the lungs via the pulmonary veins, enters the left atrium, passes through the mitral valve to the left ventricle, and is then pumped through the aortic valve into the aorta to the body.