The Cardiac Cycle

Diastole

Relaxation of the heart chambers.

Systole

Contraction of the heart chambers.

Cardiac Cycle

The sequence of events occurring in the heart during one complete heartbeat.

Phase One (Rest Phase)

The heart is relaxed or in diastole, allowing blood to flow into the atria and ventricles.

Atrioventricular Valves

Valves that open during diastole when pressure is greater in the atria than in the ventricles.

Semilunar Valves

Valves that close during diastole and open during ventricular systole due to pressure changes.

Ventricular Diastole

Phase when the ventricles are relaxed and pressure is lower compared to the pulmonary trunk and aorta.

Atrial Systole

Phase characterized by contraction of the atria, pushing the remaining blood into the ventricles.

Atrial Diastole

Phase where the atria relax as the ventricles contract.

Heart Sounds

Sounds produced by changes in blood flow during different parts of the cardiac cycle.

S1 (lubb)

First heart sound produced by closure of atrioventricular valves during ventricular systole.

S2 (dub)

Second heart sound produced by closure of semilunar valves during ventricular diastole.

S3

Third heart sound that can be heard occasionally, indicating ventricular filling.

Auscultation

The procedure of listening to the heart with a stethoscope to gather information.