Cardiac Cycle Flashcards
Name the semilunar valves
Aortic and pulmonary
Name the atrioventricular valves
Mitral (bicuspid) and tricuspid
Direction of blood flow?
From high pressure to low pressure
Name rhe first and second phases of the cardiac cycle
- Ventricular filling
2. Isovolumetric ventricular contraction
How does phase 1 of cardiac cycle end?
Atria depolarisation and contraction
What causes the AV valves to shut?
They shut at the end of the ventricular filling phase because the pressure in the ventricles is greater than the atrium
During which 2 phases are all the valves shut?
Isovolumetric ventricular contraction / relaxation
What causes rhe semilunar valves to open?
Pressure rises in ventricles in phase 2 until it becomes greater than the pressure in the aorta or pulmonary artery. The pressure difference opens the valves
Compare EDV and ESV
Edv = end diastolic volume. Maximum volume ESV = end systolic volume. Volume remaining after contraction
Why do the AV valves open following phase 4?
Phase 4 ends when the valves reopen. They reopen because the ventricles have relaxed enough that the pressure in the ventricles is less than the atria
First heart sound?
Closure of AV valves (tricuspid amd mitral / bicuspid)
Second heart sound?
Closure of semilunar valves (pulmonary and aortic)
Third heart sound?
Ventricular filling. Not usually heard unless flow is turbulent
Fourth heart sound?
Atria filling
Define regurgitation / insufficiency
The valves do not close tightly, meaning blood flows through the gap in the wrong direction. Turbulent flow
