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Diastole (/ d aɪ ˈ æ s t ə l i / dy-AST-ə-lee) is the relaxed phase of the cardiac cycle when the chambers of the heart are refilling with blood. The contrasting phase is systole when the heart chambers are contracting. Atrial diastole is the relaxing of the atria, and ventricular diastole the relaxing of the ventricles.
Diastole (at right) normally refers to atria and ventricles at relaxation and expansion together—while refilling with blood returning to the heart. Systole (left) typically refers to ventricular systole , during which the ventricles are pumping (or ejecting) blood out of the heart through the aorta and the pulmonary veins.
In the second phase of ventricular diastole, called late ventricular diastole, as the ventricular muscle relaxes, pressure on the blood within the ventricles drops even further. Eventually, it drops below the pressure in the atria. When this occurs, blood flows from the atria into the ventricles, pushing open the tricuspid and mitral valves.
Changes in diastole [ edit ] During contraction of the ventricular myocardium ( systole ), the subendocardial coronary vessels (the vessels that enter the myocardium) are compressed due to the high ventricular pressures.
Over time, hypertension can lead to serious medical problems including stroke, heart attack, and kidney failure.
As diastole ends, the ventricles begin depolarizing and, while ventricular pressure starts to rise owing to contraction, the atrioventricular valves close in order to prevent backflow to the atria. At this stage, which corresponds to the R peak or the QRS complex seen on an ECG , the semilunar valves ( aortic and pulmonary valves) are also closed .
High blood pressure, or hypertension, is defined as anything above 130 mm Hg systolic or 80 mm Hg diastolic. ... Related: What Happens to Your Body When You Exercise 30 Minutes Every Day. 2. Eat a ...
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