Question

During ventricular systole, high pressure in the ventricles pushes blood through the respective arteries. Atria and ventricles cannot contract at the same time, so the atria are in diastole during ventricular systole. Rank the events sequentially to empty the ventricles.

Atrioventricular (AV)valves close.

Ventricular ejection occurs.

Intraventricular pressure rises above arterial pressure.

Intraventricular pressure begins to increase.

Isovolumetric contraction occurs.

Semilunar valves open.

Answer 1

During ventricular systole, ventricles empty through a sequence of pressure changes and valve operation starting with an increase in intraventricular pressure, closure of the AV valves, isovolumetric contraction, rise in pressure above arterial pressure, opening of the semilunar valves, and leading to ventricular ejection.

Step-by-step explanation:

Dur­ing ven­tric­u­lar sy­s­tole, the sequence to empty the ventricles is as follows:

1. Intraventricular pressure begins to increase as the ventricles start to contract.
2. Atrioventricular (AV) valves close as the pressure in the ventricles rises above that in the atria, preventing backflow.
3. Isovolumetric contraction occurs since the ventricles are completely closed off and the volume within them remains constant despite increasing pressure.
4. Intraventricular pressure rises above arterial pressure, creating the force needed to open the semilunar valves.
5. Semilunar valves open, allowing blood to be ejected from the ventricles.
6. Ventricular ejection occurs as blood flows out through the now-open semilunar (pulmonary and aortic) valves.

The co­or­di­nation of ventricular ejection and valve operations is critical for the heart's function and is monitored via the cardiac cycle and an electrocardiogram (ECG).