The Cardiac Cycle Flashcards
What happens during late diastole?
Late diastole
Both sets of chambers relax and ventricles fill passively
What happens during atrial systole?
Atrial systole
Atrial contraction forces small amounts of additional blood into ventricles
What happens during isovolumic ventricular contraction?
Isovolumic ventricular contraction
First phase of ventricular contraction pushes AV valves closed
Does not create enough pressure to open semilunar valves
What happens during ventricular ejection?
Ventricular ejection
As ventricular pressure rises and exceeds pressure in arteries, semilunar valves open and blood is ejected
What happens during isovolumic ventricular relaxation?
Isovolumic ventricular relaxation
As ventricles relax, pressure in ventricles falls
Blood flows back into cusps of semilunar valves and snaps them closed
What is happening at A, B, C and D
A - Mitral valve closes - Inital snap back of AV valve when ventricular pressure exceeds atrial pressure
B - Aortic/ pulmonary/semi-lunar valve opens
C - Aortic/ pulmonary/semi-lunar valve closes
D - Mitral valve opens because pressure in atrium is greater than the ventricle
What is the small rise in pressure between the aortic valve closing and the mitral valve opening because of?
Dicrotic notch, small bounce in pressure due to aortic valve closing
What is A, B and C and typical values associated?
A - Systolic pressure - 120
B - Pulse pressure - 40
C - Diastolic pressure - 80
What is the mean arterial pressure?
Roughly diastolic plus one third of the pulse pressure
What is happening at stages A,B,C,D?
A - Rapid ejection
B - Slower ejection
C - Rapid filling
D - Slower filling
What is A, B and C?
End diastolic volume
Stroke volume
End systolic volume
Where on the graph does Isovolumeric ventricular contraction and relaxation occur?
Plateau
What is happening at stages A, B, C and D?
A - mitral valve opens
B - Mitral valve relaxes - pressure rises because the ventricle starts to contract
C - Aortic valve opens because pressure in ventricle exceeds the aorta (end diastolic volume)
D - aortic valve closes – End systolic volume
What is happening in the atrium during ejection phase?
Filling with blood from the lungs (pulmonary vein)
What are average values for EDV and ESV?
EDV = 140 ml
ESV = 60 ml
Stroke volume is therefore about 80 ml
What is responsible for these two sounds?
What is the cause of this abnormal sound?
Systolic murmur
What is responsible for the abnormal sound seen in the phoncardiogram?
Diastolic murmur
What is responsible for the abnormal sound on the phonocardiogram?
Septal defect
