Cardiac Cycle Flashcards
what are the two phases the heart alternates between?
the filling phase and the emptying phase
when do cardiac valves open and close?
when upstream pressure exceeds downstream pressure and closes when downstream pressure exceeds upstream pressure, the movement of valve leaflets can be detected by ECG
can heart sounds be heard? if so, how
yes, heart sounds can be heard with a stethoscope
what sounds can the stethoscope detect?
regurgitation and stenosis
what is regurgitation?
leaks in the valves that permit jets of blood to flow backward across the valvular orifice
what is stenosis?
narrowing of the valve opening forcing the blood to pass through a narrower space
During certain parts of the cardiac cycle, blood passing through either regurgitant or stenotic lesions makes characteristic sounds that are called?
murmurs
what are the four phases the cardiac cycle can be divided into?
inflow phase
isovolumetric contraction
outflow phase
isovolumetric relaxation
what is the inflow phase?
The inlet valve is open and the outlet valve is closed
what is isovolumetric contraction?
Both valves are closed, with no blood flow.
what is outflow phase?
The outlet valve is open and the inlet valve is closed
what is isovolumetric relaxation?
Both valves are closed, with no blood flow
pressure differences are larger on the left than on the right, T/F?
true
during the cardiac cycle, what is happening during the inflow phase?
the left or right ventricle is filling due to pressure difference between the atria and ventricle and gravitational forces
(Diastole)
during the cardiac cycle, what is happening during isovolumetric contraction phase?
both aortic and bicuspid valves are closed for the left/right side, pressure gradient building
(Systole)
during the cardiac cycle, what is happening during the outflow phase?
blood is squeezed into pulmonary valves
Systole
during the cardiac cycle, what is happening during the isovolumetric relaxation phase?
both valves are closed, ventricles are not receiving blood from the atria, empty (decreasing in pressure so they can receive blood from the atria)
(Diastole)
describe the pressure difference on the left side of the heart?
before the mitral valve closes the pressures between the left ventricle and left atrium are similar. Both pressures go up as left atrium squeezes toward the end of diastolic phase before the systole starts, emptying its chamber. Mitral valve starts to close as the ventricular pressure climbs again signifying the emptying of the left atrium into the left ventricle. Note time delay before opening of mitral and aortic valves, this is found in the isovolumetric contraction area and pressure is building in the left ventricle trying to reach systemic pressure like in the aorta. Once these pressures are meet (aortic pressure matching with ventricular pressure) Aortic valve opens, blood begins emptying (ventricular ejection) into the Aorta further increasing the pressure. Both pressures decrease down to baseline indicating isovolumetric relaxation with the closing of the aortic valve and opening of the Mitral valve, then it begins again
describe the pressure difference on the right side of the heart?
venous system is filling right atria until 10-15 mmHg is reached, pressure in right ventricle matches pressure with right atrium and as tricuspid valve closes, the right atria finishes squeezing itself and so isovolumetric contraction can occur, not so much pressure is required so tricuspid valve closes and pulmonic valve opens we enter ventricular ejection and then pulmonic valve closes and tricuspid valve opens indicating isovolumetric relaxation
how much pressure does it generally take to fill the ventricle from the atria?
10-15 mmHg
what indicates atrial contraction on the ECG?
P wave is the atrial contraction or depolarization, which causes blood to enter the left ventricle.
what indicates ventricular depolarization or isovolumetric contraction on the ECG ?
ventricular depolarization
why is jugular venous pressure important?
to better understand the functioning of the heart, like right sided heart failure
the mitral and tricuspid valves correspond to what s sound?
S1
the aortic and pulmonary valves correspond to what s sound
S2
how is S1 produced?
vibrations resulting from sudden tension in the AV valves and the adjacent ventricular walls produce S1
how is S2 produced?
vibrations of the large vessel walls and columns of blood produce S2 following closure of the semilunar valves. These vibrations propagate through adjacent tissues to the chest wall, where one can normally hear the first and second heart sounds through a stethoscope.
which heart sound is more prominent?
S1 is usually stronger, longer, and of lower frequency than S2.
in terms of jugular venous pressure changes caused by the cardiac cycle, what is the a peak?
is caused by the contraction of the right atrium
in terms of jugular venous pressure changes caused by the cardiac cycle, what is the c peak?
reflects the pressure rise in the right ventricle early during systole, and the resultant bulging of the tricuspid valve - which has just closed - into the right atrium.
in terms of jugular venous pressure changes caused by the cardiac cycle, what is the v peak?
related to filling of the right atrium against a closed tricuspid valve, which causes right atrial pressure to rise. As the tricuspid valve opens, the v peak begins to wane.
what are the three peaks in the jugular pulse wave?
a,c,v
