The Cardiac Cycle Flashcards
What is cardiac systole?
Contraction of the heart
What is cardiac diastole?
Relaxation of the heart
How long does diastole last?
2/3rds of each beat
How long does systole last?
1/3 or each beat
How many stages is diastole split into?
3
How many stages is systole split into?
3
How many distinct stages of the cardiac cycle are there?
7
What are the names of the 7 distinct stages of the cardiac cycle?
Atrial Systole Isovolumetric contraction Rapid ejection Reduced ejection Isovolumetric relaxation Rapid passive filling Reduced passive filling
What happens during ventricular relaxation?
The ventricles fill with blood
What happens during ventricular contraction?
The ventricles generate pressure and then. Eject the blood into the arteries
What is the end diastolic volume?
The volume of blood in the ventricles just before systole
What is the end systolic volume?
The volume of blood that remains in the ventricles after systole has occurred?
What is the stroke volume in relation to EDV and ESV?
The stroke volume is the EDV - ESV
This is because the stroke volume is the amount of blood which is ejected from the ventricles with each contraction of the heart
What are the common figures for EDV, ESV and SV?
EDV = 120 ml
ESV = 50 ml
Therefore stroke volume = 70ml
What is the ejection fraction?
The (SV / EDV ) x 100
What is the normal range for the ejection fraction?
50-70%
What happens to the ejection fraction during heart failure?
The ejection fraction decreases to about 30%
How is the ejection fraction used clinically?
It is used to assess the degree of heart failure a patient may have
Where is the tricuspid valve located?
Between the right atrium and right ventricle
Where is the bicuspid or mitral valve located?
Between the left atrium and the left ventricle
Where is the pulmonary valve located?
Between the right ventricle and the pulmonary artery
Where is the aortic valve located?
Between the left ventricle and the aorta
What is atrial systole?
Contraction of the atria to top up the volume of blood in the ventricle
What wave on the ECG correlates with atrial systole?
P wave
What might be heard during atrial systole?
An abnormal heart sound due to valve incompetence of the semilunar valves
In what conditions might a sound be heard during atrial systole?
Congestive heart failure, pulmonary embolism or tricuspid incompetence
What does the QRS complex symbolize?
Depolarization of the ventricular muscle
What is isovolumetric contraction?
When there is contraction of the ventricles to build pressure (isometric contraction), but no change in the volume of blood in the ventricles
What heart sound is heard during isovolumetric contraction?
Lub
What is the status of the AV and SL valves during isovolumetric contraction?
They are all closed