Cardiac Cycle Flashcards
WD Phase A
Atrial Systole
- atria contract
- final phase of ventricular filling
- associated with 4th heart sound
- atrial pressure is reflected back to veins causing venous pressure “a” wave
WD Phase B
Isovolumetric Ventricular Contraction
- ventricles contract
- ventricular pressure increases
- AV valves close
- produces 1st heart sound
- increased pressure causes bulge of AV valve into aorta, causing atrial “c” wave
First Heart Sound
- closing of mitral and tricuspid (AV) valves
- ventricular contraction causes theses to close
- prevents blood from backing into atria
- onset of ventricular systole
WD Phase C
Rapid Ventricular Ejection
- ventricles contract
- pressure increases and reaches max
- aortic valve opens
- blood ejected into arteries
- aortic pressure increases and reaches max
WD Phase D
Reduced Ventricular Ejection
- ventricles eject blood into aorta at slower rate
- ventricles do not empty completely
- aortic pressure begins to fall
End-Diastolic Volume
ventricular volume after filling
Afterload
pressure against which the heart pumps blood into the circulation
End-Systolic Volume
the amount of blood remaining in the ventricle at the end of systole
Ejection Fraction
the proportion of EDV that is ejected
SV/EDV
WD Phase E
Isovolumetric Relaxation
- ventricles relaxed
- ventricular pressure decreases
- aortic valves closed
- second heart sound
- volume is constant (ESV)
- atrial pressure increases due to venous return (“v” wave)
Second Heart Sound
- semilunar valves closing
- pressure from ventricle and aorta
- when pressure of aorta is greater, the valves are pushed closed
- onset of ventricular diastole
WD Phase F
Rapid Ventricular Filling
- ventricles relaxed
- AV valves open
- ventricle fills with blood
- volume increases
- ventricular pressure low
- may produce third heart sound
WD Phase G
Rapid Ventricular Filling
- ventricles relaxed
- final phase of ventricular filling
Lub-whistle-dup
- stenotic semilunar valve
- systolic timing
Lub-dup-whistle
- stenotic AV valve
- diastolic timing
Lub-swish-dup
- insufficient AV valve
- systolic timing
Lub-dup-swish
- insufficient semilunar valve
- diastolic timing
Stenotic Valve
- stiff, narrow valve that does not open completely
- blood must be force through at high velocity
- produces whistling sound
Insufficient Valve
- valve cannot close completely
- blood flows backwards and collides with the blood moving forward
- produces swishing sound
