SSM Heart - Aina Aqilah

BM21110064
SSM Assignment
6.0 PHYSIOLOGY OF HEART
Cardiac Cycle and its correlations with ECG
The cardiac cycle refers to the complete sequence of events that occur in the heart, from the
beginning of one heart beat to the beginning of the next. The cardiac cycle consists of two
phases:
The diastolic phase, during which the ventricles fill with blood. Diastole consists of four stages:
– isovolumetric relaxation
– rapid ventricular filling
– slow ventricular filling
– atrial contraction.
The systolic phase, during which the ventricles contract and eject blood into the aorta and
pulmonary artery. Systole consists of two stages:
– isovolumetric contraction
– ejection.
Traditionally, the cardiac cycle is described from late diastole, when the atria and ventricles are
relaxed and the AV valves are open:
●
Slow ventricular filling.
The pressure within the atria is slightly higher than intraventricular pressure. The AV valves are
therefore open, allowing blood to flow slowly from atrium to ventricle.
●
Atrial contraction.
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