The Cardiac Cycle Flashcards
What are the 5 stages of the cardiac cycle?
Passive Filling Atrial Contraction Iso-volumetric ventricular contraction Ventricular Ejection Iso-volumetric Ventricular Relaxation
At which pressure does the aortic valve close during passive filling?
80mmHg
The ventricles become 50% full by passive filling.
True/False?
False
80%
When on an ECG does the atria contract?
between P wave and QRS complex
What is left in the atria after contraction?
the End Diastolic Volume - roughly 130ml
When on an ECG does ventricular contraction begin?
after the QRS complex
When do the AV valves shut?
when ventricular pressure is greater than atrial pressure
What produces the first heart sound?
closure of the AV valves
Why is it called “Isovolumetric” contraction?
the aortic valve is shut and the AV valves have just shut but the pressure/tension rises around the closed volume = isovolumetric
When do the aortic/pulmonary valves open?
When ventricular pressure > aorta/pulmonary artery pressure
What volume is ejected from the ventricles during ventricular ejection?
Stroke volume
What is left in the ventricles after ventricular ejection?
End Systolic Volume (ESV)
Which wave occurs on ECG after ventricular ejection?
T wave (ventricular repolarisation)
What produces the second heart sound? And why does it happen?
closure of the aortic/pulmonary valves
After ventricular ejection, ventricles relax and their pressure starts to fall. When v. pressure < aortic/pulmonary artery pressure - valves shut
What does the vibration of the aortic/pulmonary valves closing cause?
dicrotic notch in the aortic pressure curve
