Cardiac Cycle
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Transcript Cardiac Cycle
CARDIAC CYCLE
Cardiac Cycle
Refers to pattern of ;
Systole (contraction)
Diastole (relaxation)
Shown by the heart in one complete cycle
On average this 1 cardiac cycle lasts 0.8
seconds (based on 75 bpm)
Diastole
Return of blood from venae cavae and
pulmonary veins to atria
Causes atrial volume of blood to increase
Eventually atrial pressure > ventricular pressure
= AV valves are pushed open
Atrial systole
Atria (R&L) contract simultaneously pushing
remainder of blood into ventricles
Ventricles are still in diastole and SL valves
are closed
Ventricular systole
Contraction of ventricles and closure of AV
valves. (‘lubb’)
Blood pressure in ventricles > pressure in arteries
= SL valves pushed open and blood pumped out
of heart into aorta and pulmonary arteries.
Diastole
Higher pressure in arteries close SL valves
again. (‘dupp’)
Cardiac cycle repeats
Heart Sounds
Normal
https://www.youtube.com/watch?v=xS3jX1FY
G-M
Murmur
https://www.youtube.com/watch?v=qCG_xoS
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