Cardiac cycle Flashcards
Illustrate the sequence of changes in pressure and volume in the chambers of the heart throughout the cardiac cycle.
- late diastole- both sets of chambers are relaxed and ventricles fill passively.
- atrial systole- atrial contraction forces a small amount of additional blood into ventricles
- isovolumetric ventricular contraction- ventricle contraction pushes AV valves closed but doesnt creat enough pressure to open semilunar valves
- ventricular ejection- as ventricular pressure rises and exceeds pressure in arteries the semilunar valves open and blood is ejected.
- isovolumetric ventricular relaxation- ventricles relax, pressure falls. blood falls back into cusps of semilunar valves and snaps them closed and cycle repeats
Interpret a pressure-volume loop.
Explain the generation of the heart sounds (phonocardiogram).
what is the diastole phase
filling of atrium or ventricles
what is the systole phase
ejection phase of atrium or ventricles
what is the a wave
atrial contraction
what is the c wave
when mistrial valve closes and because its quite flappy it will budge into the left atrium increasing pressure
what is the V wave
blood returning from lungs into the left atrium which has a low volume so when blood flows in pressure gradually increases and increases
what is pulse pressure
difference between diastolic and systolic of the aorta
what is mean arterial pressure
is a third of the way between diastolic and systolic
what is the dicrotic notch
It is universally used to demarcate the end of systole and the beginning of diastole in these arteries. Due to the elastic properties of the aorta it decreases slowly
what is it called between the distance of end systolic volume to end of diastolic volume
stroke volume however mainly is affected by size of the person
what is the ejection fraction
stroke volume divided by the end diastolic volume which is a percentage of the blood in the ventricle pumped out with each contraction. in an unhealthy person this would be below 60%
describe isometric contraction phase
mitral and aortic values are closed
describe rapid ejection phase
pressure in left ventricle exceeds pressure on the aorta and pushes aortic value open and blood is pumped out of left ventricle quickly so volume is decreased rapidly