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As the ventricle begins to relax, the pressure in the ventricle begins to decline. The pressure in the artery (which now has all the ejected blood) is now greater than that in the ventricle. The blood now closes the semi-lunar valve as it tries to go from the artery into the ventricle preventing any back-flow. Although the pressure in the ventricle is declining, it is still greater than that in the atria so the AV valves are still closed. Thus as the ventricle is relaxing, the volume of blood in the ventricle is not changing. This stage will continue until the ventricular pressure becomes lower than the atrial pressure and the filling stage starts again.
http://academic.kellogg.edu/herbrandsonc/bio201_mckinley/f22-11_cardiac_cycle_c.jpg
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When does Isovolumetric relaxation and ventricular filling take place?
Ventricular Diastole
What happens to the volume of blood in the ventricle during the period of isovolumetric contraction?
Both ventricular contraction and atrial diastole take place.
During which 2 periods of the cardiac cycle do the heart muscle fibers exhibit isometric contractions?
Isovolumetric contraction and Isovolumetric Relaxation
What is equivalent to the ventricular volume during isovolumetric contraction?
The end diastolic volume (EDV)
Is the 2nd heart sound in the period of isometric contraction?
no. it occurs at the beginning of isovolumetric relaxation.
During the isovolumetric relaxation phase of the cardiac cycle the AV valves are and the semilunar valves are?
closed and closed
What happend during isovolumetric contraction?
There are 3 phases in the cardiac cycle: 1) Ventricular filling: mid-to-late diastole; 2) Ventricular systole; and 3) Isovolumetric relaxation: early diastole. In phase two, ventricular systole, the atria relax and the ventricles begin contracting. Their walls close in on the blood in their chambers, and ventricular pressure rises closing the atriaventricular (AV) valve. Because, for a split second, the ventricles are completely closed chambers and blood volume in the chambers remain constant, it is called the isovolumetric contraction phase.Info gathered from Marieb's Human Anatomy and Physiology 8th edition: Chapter 18 Cardiovascular System
What heart valves are closed during systole?
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)
What is the quiescent period as related to the heart?
The quiescent period of the heart is after the ventricle has completed isovolumetric relaxation (or early diastole). In other words, it is after ventricle systole (when the ventricle has completed contraction). During the quiescent period the ventricles are relaxed and begin to fill up with blood. Interestingly, when considering the time of each event (atrial systole, ventricular systole) most of the cardiac cycle has the heart in this relaxation/ quiescent period.
What recoil helps keep blood flowing during ventricular relaxation?
The Elastic Arteries :)
The contraction of the ventricles is referred to as systole and the period of ventricular relaxation is called?
I believe that is called diastole, in contrast to systole, the contraction of the heart muscles.
What portion of the cardiac cycle is shortened by this more rapid heart rate?
The ventricular relaxation period.
