Download Cardiac Cycle:

Cardiac Cycle:
Series of events that constitute a
complete heartbeat
Cardiac Cycle Explained

Khan Academy

https://www.youtube.com/watch?v=y5maH
DAkzUs
Cardiac Cycle Diagram
Heart Sounds

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“Lubb” = ventricular contraction; A-V valves
close
“Dupp” = ventricular relaxation; pulmonary
and aortic valves close
Events
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Atria relax and blood flows in
Chambers fill which increases pressure
inside causing A-V valves to open
Blood flows into ventricles (70-80% of
entering blood)
Events, Cont’d
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Atrial walls contract (atrial systole) which
pumps the remaining 20-30% of blood into
the ventricles
Atrial walls relax (atrial diastole)
Events, Cont’d

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Ventricles contract (ventricular systole);
A-V valves close and blood is pumped out
Ventricles relax (ventricular diastole);
A-V valves open