Cardiac Cycle: Pressure and Volume Chahnges Flashcards
What are the atrioventricular valves?
Bicuspid (mitral) valve (LA-LV)
Tricuspid valve (RA-RV)
What are the semi-lunar valves?
Pulmonary valve (RV-pulmonary artery)
Aortic valve (LV-aorta)
What is the contractile phase called?
Systole
What is the relaxation phase called?
Diastole
Which is longer; diastole or systole?
Diastole
What happens during passive filling?
AV valves: open
SL valves: closed
What happens during atrial contraction?
AV valves: open
SL valves: closed
What happens when pressure rises?
Flow rises
Does the volume change?
Volume stays the same
What happens during isovolumetric contraction?
AV valves: closed
SL valves: closed
What happens during ventricular ejection?
AV valves: closed
SL valves: open
What triggers the semi-lunar valves to open?
Pressure increases so blood needs to be ejected
What happens during isovolumetric relaxation?
AV valves: closed
SL valves: closed
When does ejection of blood occur?
When LV pressure exceeds aortic pressure
What is normal stroke volume
~80ml
What is the equation for cardiac output and what does it signify?
CO=HR x SV
Volume of blood each ventricle pumps per minute
How do we find the stroke volume?
SV = EDV - ESV
EDV - end diastolic volume
ESV - end systolic volume
When does the blood volume start to decrease?
As left ventricular pressure starts to exceed aortic pressure
Where does the lub and dup sound come from?
Sound from the valves closing
What side of the ventricles has higher pressure and why?
Left ventricle is higher
Left wall is thicker - needs a higher force of contraction due to having to eject blood against higher aortic pressure
Are the left and right ventricles’ stroke volumes different or the same?
Stroke volumes are equal - same volume of blood being pumped
What influences the fluctuation in atrial pressures during cardiac cycle?
Atrial/ventricular systolic and diastolic events
Atrioventricular valve events
Abnormal cardiac pump function
What is the effect of valves being absent between the atria and their respective veins?
Venous pressure and atrial pressure are the same
Can assess jugular vein pressure for an insight into atrial pressure
What does the a-wave refer to?
Right atrial contraction
What does the c-wave refer to?
Bulging of tricuspid valve into right atrium and expansion of carotid artery
Beginning of systole - not contracting yet
What does the x-descent refer to?
Right atrial relaxation and right atrial stretching
downward movement of the base of the ventricle
What does the v-wave refer to?
Right atrial filling
v - ventricular systole
What does the y-descent refer to?
Right atrial emptying into right ventricle
Why is the tricuspid valve closed for a large part of the cardiac cycle?
Diastole phase is longer than systole phase
