Lecture 15 Flashcards
When is the beginning of the cardiac cycle?
The beginning of the QRS wave - ventricular systole.
Describe isovolumetric contraction?
This is the phase between the start of ventricular systole and the opening of the semilunar valves (pulmonary and aortic valves). This contraction coincides with he peak of the R wave, the first heart sound and the earliest rise in ventricular pressure.
Describe the ejection phase?
When the ventricles are pumping out the blood. LV - valve opens and enables ejection of blood into the aorta (two phases: rapid and reduced phase). In the reduced ejection phase, the flow from the aorta is greater than the rate of the LV outflow.
Describe isovolumetric relaxation?
When the aortic valve closes there is a notch on the aortic pressure curve. This is the period between closure of the semilunar valves and the opening of the AV valves. This coincides with the second heart sound as well.
Describe the filling phase?
This occurs immediately after opening of the AV valves. The LV pressure decreases below LA Pressure. There is a rapid flow of blood from the atria to the relaxing ventricles.
Describe diastole?
Phase of slow ventricular filling. Blood returns from the peripheral veins.
Describe atrial systole?
Occurs just after the P wave. This completes the period of ventricular filling. This depends on HR - increased HR means reduced time on ventricular filling.
