Systole (cardiac physiology)

Systole is the phase of the cardiac cycle when heart muscle contracts and ejects blood from the chambers. Ventricular systole drives blood into the pulmonary artery and aorta.

Cardiac cycle: The sequence of electrical and mechanical events in one heartbeat, including filling and ejection. Systole is the contraction-and-ejection phase within this repeating sequence.
Diastole: The phase of the cardiac cycle when heart chambers relax and fill with blood. It alternates with systole and supplies the blood ejected during contraction.
Systolic blood pressure: The maximum arterial pressure reached during ventricular contraction and ejection. It records the arterial pressure peak generated during systole.
Isovolumetric contraction: The brief phase when ventricles contract while all heart valves are closed, raising pressure without changing volume. It begins ventricular systole before blood is ejected.
Ventricular systole: The period when the ventricles contract and eject blood into the pulmonary artery and aorta. This is the principal pressure-generating part of systole.
Blood pressure: The force exerted by circulating blood against the walls of blood vessels. Arterial pressure rises during ventricular ejection and falls during relaxation.
Pulse pressure: The difference between systolic and diastolic arterial blood pressure. Its value depends partly on the pressure rise produced by ventricular ejection.
Isovolumetric relaxation: The brief phase when ventricles relax with all valves closed, causing pressure to fall without changing volume. It follows ejection and marks the transition out of systole.
Atrial systole: The period when the atria contract, moving additional blood into the ventricles. Atrial contraction occurs at the end of ventricular filling, before ventricular systole.
Ventricular pressure: The pressure of blood inside a heart ventricle, which changes throughout the cardiac cycle. Its rise above arterial pressure opens the outflow valves.

Linked from 4 pages

PulseBroader topic: The pulse wave begins as the left ventricle ejects blood during this phase.