Cardiac Cycle Flashcards
What are the four phases of the cardiac cycle?
Inflow phase, isovolumetric contraction, outflow phase, isovolumetric relaxtion
What is diastole
ventricle relaxation
What is systole
ventricle contraction
What does iso-volumetric mean?
no volume change
What happens to the valves during iso-volumetric changes
all valves are close
When does the AV valve close
during outflow phase
Why does the AV valve close during outflow opahse
prevent backflow into the atria
What is length systole at rest
300ms
What is the effect of diastolic phase decreasing on HR
when diastolic phase decreases, HR increases
What the differences between the left and right ventricles
left ventricle has higher pressure, more muscular
What is the ventricular volume in end phase (inflow)
high
What is the ventricular volume in end phase (inflow)
low
What is the atrial pressure during end phase (inflow)
higher than ventricular pressure
Describe the flow of blood during end phase (inflow)
blood moves from atria into ventricles through open AV valve down pressure gradient
What is stroke volume
volume of blood expelled in each heartbeat
What contracts during end phase (inflow)
atria
How much blood moves into the ventricle during end phase (inflow)
20% of stroke volume
Describe the system in phase 2 (isovolumetric contraction)
closed
Why does the AV valve close during phase 2 (iso contraction)
increased ventricle pressure
Describe the pressure in the ventricles during phase 2 (isovol contraction)
ventricles contract so ventricle pressure increases
Describe the movement of blood during phase 2 (isovol contraction)
NO movement!!!!
What is the end systolic volume typically at rest
50mls
What is the end systolic volume?
ventricles are never empty, remaining volume
Describe the changes in the ventricle during phase 3 (outflow)
ventricle pressure is increasing, ventricle blood volume decreases
Describe the movement of blood during phase 3 (outflow)
blood moves out ventricle into aorta
What valve is opened at the end of phase 2 (isovol contraction)
aortic semi lunar valve
Describe the aortic pressure during phase 3 outflow
increases
Describe the changes to the atria during phase 3 (outflow)
Atria fill with blood and pressure rises
Describe blood flow during phase 4 (isovol relaxation)
no blood flow
Which phases have no change in blood volume
2 and 4
What causes the semi lunar valve to close
back flow of blood
Describe ventricle changes during phase 4 (isovol relaxation)
no volume changes, muscles relax, pressure decreases
What valves are open during phase 4
none
What is the last part of the cardiac cycle
early phase 1 inflow
Describe blood flow during early phase 1 inflow phase
blood moves into ventricles from atria
Describe ventricle pressure in early phase 1 inflow
drops slightly below atrial pressure
What valve opens during early phase 1 inflow
mitral valve
Describe the volume changes in the ventricle during early phase 1 inflow
large increase in volume, hydrostatic pressure generated
Describe atrial pressure during early phase 1 inflow
rises due to inflow of blood larger than outflow
What is the P wave associated with
atrial contraction
What is the QRS complex associated with
ventricular contraction
What is the T wave associated with
ventricular relaxation
What is reduced in heart failure
ejection fractions
