Phases Of The Cardiac Cycle Flashcards
How many phases are there in the cardiac cycle?
7 phases
As heart rate increases, what happens to the time spent in systole and diastole?
Systole ALWAYS STAYS THE SAME
Diastole gets shorter as heart rate increases- the heart spends less time relaxing and filling
What happens to atrial pressure during atrial contraction?
What wave represents this change in pressure on a Wiggers diagram?
It rises
“A wave”
Atrial contraction accounts for what percentage of ventricular filling? What accounts for the rest?
10%
The other 90% is driven the passive process of the ventricle “sucking in blood” once the mitral valve opens
Atrial contraction is represented by what on an ECG?
“P wave”- onset of atrial depolarisation
During atrial contraction mitral and tricuspid valves are ________ and aortic and pulmonary valves are ________
Open
Closed
What stage follows atrial contraction in the cardiac cycle?
Isovolumetric contraction
What causes the mitral valve to close during isovolumeteric contraction?
What is the importance of this closure with regard to clinical practice?
When intraventricular pressure rises above atrial pressure
This is the first heart sound (S1) heard with a stethoscope “Lub”
What does the term “isovolumetric” mean in relation to “Isovolumetric contraction” of the heart?
That there is no change in ventricular volume
During isovolumetric contraction, the mitral and tricuspid valves are ___________ and the pulmonary/aortic valves are ___________.
Closed
Closed
What can be seen during isovolumetric contraction on the ECG?
What does this represent?
QRS complex
The onset of ventricular depolarisation
What phase followed isoventricular contraction in the cardiac cycle?
Rapid ejection phase
How does rapid ejection occur?
The intraventricular pressure exceeds the pressure in the aorta
What happens to ventricular volume during rapid ejection phase?
Ventricular volume rapidly decreases
