Cardiac Cycle Flashcards
What is the normal pressure of the right atrium?
2 mm Hg
What is the systolic pressure of the right ventricle?
25 mm Hg
What is the diastolic pressure of the right ventricle?
0 mm Hg
What causes ventricular filling?
small pressure differential (1-2 mm Hg on right and 5 mm Hg on the left) between the atria and ventricles during diastole.
What is the flow of blood?
enters the right atrium via the superior and inferior vena cava, passes through the tricuspid valve (right AV valve) to the right ventricle, through the pulmonary valve, through the pulmonary artery, to the lungs, back through the pulmonary veins, into the left atrium, through the mitral valve (left AV valve), into the left ventricle, and out through the aortic valve to the aorta and systemic circulation.
What are the pressures of the pulmonary artery?
systolic 20/ diastolic 6
What is the systolic pressure of the left ventricle?
120 mm Hg
What is the diastolic pressure of the left ventricle?
0 mm Hg
What is the pressure (systolic/diastolic) of the aorta?
120/80 mm Hg
If you heart rate is 75 beats/min, how long is one cardiac cycle?
(60 sec/min)* (1 min/75 beats)= 0.8 sec
How long is systole in relation to the cardiac cycle?
about a 1/3 of the time (so if cardiac cycle is 0.8 sec/beat then systole= 0.27 sec). Ejection itself= 0.22 sec.
Where does the cardiac cycle spend most of its time?
diastole= 0.53 sec.
Into what is systole divided?
Isovolumetric contraction= 0.05 sec
Ejection= 0.22 sec (rapid and reduced).
What is isovolumetric contraction?
the time during systole in which there is no change in volume as both mitral and aortic valves are closed, right before contraction.
Into what is diastole divided?
isovolumetric relaxation= 0.12 sec
Filling= 0.41 sec (rapid and reduced)
What is isovolumetric relaxation?
the time during diastole in which there is no change in volume as both mitral and aortic valves are closed, right before ventricular filling.
Where does the heart spend most of its time in systole and diastole?
systole= ejection diastole= filling
In late diastole, is atrial or ventricular pressure higher?
atrial (so the blood can flow through the mitral valve into the ventricle).
What happens to aortic pressure during late diastole?
it decreases as blood fills capillaries and veins throughout the body.
What causes the mitral valve to close?
as soon as the ventricular pressure increases beyond the atrial pressure (beginning of systole).
What cause the first heart sound (S1)?
mitral and tricuspid valves closing.
Why does the ventricular pressure rise so rapidly at the beginning of systole?
because the ventricle is isometrically contracting against 2 closed valves (mitral and aortic).
Where is the rate of rise in pressure (dPdT) the highest?
during systolic isometric contraction.
What causes the aortic valve to open?
when ventricular pressure exceeds the aortic pressure. This marks ejection.