How does the heart control diastole and systole?

The heart controls diastole and systole through a coordinated sequence of electrical impulses and mechanical actions. During diastole, the heart muscles relax, allowing the chambers to fill with blood, primarily driven by the pressure gradient. In systole, electrical signals from the sinoatrial (SA) node trigger the ventricles to contract, pumping blood out to the lungs and the rest of the body. This rhythmic cycle is regulated by the autonomic nervous system, which adjusts heart rate and force of contraction as needed.