Cardiac Cycle Flashcards
Blood moves according to what gradient?
down pressure gradient
Where do pressure changes occur?
- left atria
- left ventricle
- left aorta
Where do volume changes occur?
ventricle
Where do electrical changes occur?
atria and ventricle
What are the 7 phases of the cardiac cycle?
- atrial systole
- ventricular isovolumetric contraction
- rapid ventricular ejection
- slow ventricular ejection
- ventricular isovolumetric relaxation
- ventricular filling
- diastasis
What occurs in phase 1 of the cardiac cycle?
- P-wave: atrial depolarization precedes and triggers atrial contraction
- a wave: developed atrial pressure
- blood moves from atrial chamber and fill the ventricle (increase pressure)
- AV valves close -> 1st heart sound ->ends phase 1
What occurs between phase 1 and 2?
no change in blood volume in chambers (isovolumic)
What occurs in phase 2 of the cardiac cycle?
- QRS wave: ventricular depolarization precedes and triggers rapid ventricular contraction
- contraction causes rise in developed ventricular pressure
- input (A-V) and output (aortic) -> valves clsoe, no blood moves
- aortic valves open -> phase 2 ends
What occurs in phase of 3 the cardiac cycle?
- blood ejected from the ventricle
- ventricular contraction is transmitted mechanically to the atria producing the c wave
- t wave: ventricular repolarization initiates ventricular relaxation -> end of phase 3
What occurs in phase 4 of the cardiac cycle?
- relaxation causes decrease in ventricular pressure
- ventricle slowly empties
- return of blood begins artrial filling and increased atrial pressure
- aortic valve closes -> 2nd heart sound -> end of phase 4
What occurs in phase 5 of the cardiac cycle?
- input and output valves are closed, no ventricular blood moves
- AV valves opens -> end of phase 5
What occurs in phase 6 of the cardiac cycle?
- ventricular pressure is below atrial
- with AV valve open, atrial blood rapidly flows into the ventricle (turbulant sound)
- 3rd heart sound caused by rapid turbulant flow
What occurs in phase 7 of the cardiac cycle?
- AV valve is open, venous blood is slowly filling atrial and ventricular chambers
- decreased, slow ventricular filling
- aortic pressure slowly declines
- atrial contraction-> end of phase 7 and back to phase 1
What is stroke volume?
end diastolic volume - end systolic volume
As the volume of the ventricular tissue increases, what happens to the length and pre-load?
they both increase
Increasing length by stretching increases what?
passive force
Chamber pressure increases with what?
contractility
In the pressure volume loop, when does ventricular filling occur?
between when the mitral valve opens and when the mitral valve closes
In the pressure volume loop, when does isovolumetric contraction occur?
when mitral valve closes and aortic valve opens
In the pressure volume loop, when does ventricular ejection occur?
when aortic valve opens and aortic valve closes
In the pressure volume loop, when does isovolumetric relaxation occur?
when aortic valve closes and mitral valve opens
