Yes, when the AV valves open and blood begins to enter the ventricles they are in isotonic relaxation. This is why the pressure does not increase in the ventricles during this time.
Systolic Pressure occurs during ventricular ejection.Diastolic Pressure occurs during ventricular relaxation.
Ventricular Diastole
In late diastole (relaxation phase), the semilunar (pocket) valves close, due to decreasing arterial pressure, to prevent blood flowing back into the ventricles. These stay closed during atrial systole. (But open again during ventricular systole.)Then, as the ventricles contract during ventricular systole, the bicuspid and tricuspid valves close to prevent blood from flowing back to the atria.So, it really depends on which phase of the contraction we are looking at.(Ed: format)
Extrasystole is an extra ventricular systole that happens during the begging of relaxation (repolarization). Since the cardiac is able to depolarize only after repolarization, any stimulus upon the repolarization period created an increased ventricular contraction or which is also called extrasystole but not a new contraction.
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The relaxation phase of the heart is when there is no compression pressure on the heart.
I believe that is called diastole, in contrast to systole, the contraction of the heart muscles.
The Elastic Arteries :)
relaxation phase
diastole
The diastolic phase is shortened by a more rapid heart rate. This is the phase when the heart muscle relaxes and fills with blood. A faster heart rate reduces the time available for the heart to refill, impacting cardiac output.
this is called the diastolic pressure meaning when the heart is in diastole. The diastolic number is the bottom number in common blood pressure. i.e. in a pressure 120/80 the lowest measured pressure is 80mmHg during ventricular relaxation