What happens during the systole phase when all valves are closed?

During the systole phase when all valves are closed, the ventricles contract, leading to an increase in pressure within the ventricular chambers. This rise in pressure is critical as it prepares the blood to be ejected from the heart. As the ventricular pressure exceeds the pressure in the aorta, it causes the aortic valve to open, allowing blood to flow from the ventricles into the systemic circulation. This phase is essential for the effective pumping action of the heart, ensuring that oxygenated blood reaches various tissues and organs throughout the body.

In contrast, during this phase, the ventricles are not filling with blood; therefore, there is no blood flow into the ventricles from the atria. Additionally, pressure does not rise in the atria since they are typically in a relaxed state during ventricular contraction. While the blood does indeed eventually get pumped to the lungs, this occurs during diastole when the right ventricle contracts, not during the closed-valve systole phase when all valves are sealed off.