The cardiac cycle ND Flashcards
4 phases of the cardiac cycle?
Atrial diastole + systole
Ventricular diastole + systole
There is overlap though ^
What happens overall in diastole?
heart muscle relaxes and allows the chambers to fill with blood
What happens overall in systole?
heart muscle contracts and pumps blood from the chambers into the arteries
What are the specific phases, in order, of systole?
- Atrial systole
- Isovolumic ventricular contraction
- Ventricular ejection
What happens in atrial systole?
Atria contract
This forces a small amount of blood into the ventricles (which are already pretty much full from Diast)
What happens in isovolumic ventricular contraction?
Ventricles contract and close the AV valves
However, not enough pressure is generated to open the semilunar valves to the arteries
What happens in Ventricular ejection?
Ventricles continue to contract
Pressure in V exceeds pressure in arteries so blood is pushed through the semilunar valves
What is the atria doing at the time of ventricular systole?
atrial diastole so it’s doing fuck all
What causes the mitral valve to close?
Ventricular pressure exceeding atrial pressure
Why does atrial pressure show a blip on a graph, during ventricular systole?
Ventricular contraction causes mitral/tricuspid valve to balloon backwards slightly and pushes on the blood in the atrium
What happens in terms of pressure & volume during isometric contraction?
Isometric = isovolumic
Volume constant
Pressure increases (but not such that it exceeds arterial pressure)
What happens to the volume of blood in the ventricle once the aortic valve opens?
Decreases
Rapid ejection phase & slow ejection phase
Volume Graph shows a ‘quarter pipe’ shape like youd get on a ski run
