In which stage are the ventricles entirely closed ventricula

In which stage are the ventricles entirely closed? ventricular systole isovolumetric relaxation atrial systole isovolumetric contraction For a very brief moment during the isovolumetric contraction phase, the 4 valves of the heart are closed. True False Choose the correct association of the various components in relationship to the ANS influence on the heart. SANS: SA NODE: RELAXATION SANS: AV NODE: FIGHIT OR FLIGHIT PANS: SA NODE: HEART RATE: 150 BEATS/MIN. PANS: AV NODE: AGGRESSION

Solution

18: Ventricular systole.
The first heart sound is produced during this stage because of the closing of the AV valve. The ventricular pressure rises and the semilunar valves also close giving rise to a completely closed ventricular chamber.

19: True
The artrioventricular valves (tricuspid and mitral) closes in order to stop the back flow of the blood. Towards the end of diastole, the semilunar valves (aortic and pulmonary) are also closed and this lasts for approximately 0.03s which drastically raises the ventricular pressure. This process ensures to maintain correct unidirectional flow of the heart and circulatory system.

20: