The Cardiac Cycle Flashcards
What are the steps of systole?
Atrial systole - atrial contraction forces a small amount of additional blood into the ventricles.
Isovolumic ventricular contraction - the mitral and tricuspid valves close.
Ventricular ejection - ventricular pressure rises, the aortic and pulmonary valves open, and blood is ejected.
What are the steps of diastole?
Isometric ventricular relaxation - ventricular pressure falls. The aortic and pulmonary valves close.
Late diastole - all chambers relax and fill with blood.
What is the pressure of the LV in the cardiac cycle?
Small blip - atria contract.
The mitral valve closes and pressure rises.
Once it is higher than aortic pressure, the aortic valve opens, and blood moves into the aorta.
Intracellular [Ca2+] decreases, causing muscle relaxation, and pressure falls, closing the aortic valve.
When Vp < Ap, the mitral valve opens, and blood from the atrium enters the ventricle.
What is the pressure of the aorta in the cardiac cycle?
Slowly decreases - elastic wall maintains pressure.
Matches left ventricular pressure, once risen.
Dicrotic notch - elastic recoil.
What can be measured from aortic pressure?
MAP - 1/3rd of the way between diastolic and systolic pressures.
Pulse pressure = systolic - diastolic.
What is the a wave of the LA?
Caused by atrial contraction.
What is the c wave of the LA?
The mitral valve closes and bulges into the LA, increasing pressure.
When the aortic valve opens and blood flows from the LA into the artery, pressure decreases.
What is the v wave of the LA?
Blood slowly returns from the lungs to the LA, until the Ap > Vp and then the mitral valve opens. This allows blood to flow from the LA into the LV.
What are the rapid ejection phase and slower ejection phase?
REP - blood is quickly pumped out of the LV, when LV pressure is higher than aortic pressure, and the aortic valve is open.
SEP - when REP tails off.
What are the rapid filling phase and slower filling phase?
RFP - blood quickly fills the LV, when Ap > Vp, causing the mitral valve to open, and blood is pushed from the LA into the LV.
SFP - when RFP tails off.
How is the ejection fraction calculated?
End diastolic volume / stroke volume.
SV = EDV - ESV.
What heart sounds occur?
1st - closure of the mitral and tricuspid valves.
2nd - closure of the aortic and pulmonary valves.
3rd - rapid passive filling phase.
4th - active filling phase.
What is a systolic murmur?
Additional sound between the 1st and 2nd heart sounds.
The stenosis of aortic or pulmonary valves.
The regurgitation through mitral or tricuspid valves.
What is a diastolic murmur?
Additional sound after the 2nd heart sound.
The stenosis of mitral or tricuspid valves.
The regurgitation through aortic or pulmonary valves.
What causes a continuous murmur?
Patent ductus arteriosus.
