ANATOMY

Detailed explanation-1: -In the diastole phase, blood returns to the heart from the superior and interior vena cava and flows into the right atrium. The pressure in the right atrium increases as blood flows into it.

Detailed explanation-2: -During the mid portion of diastole (diastasis), the pressure in the left atrium and LV equilibrates, and mitral flow nearly ceases. Late in diastole, atrial contraction increases the atrial pressure, producing a second atrial-to-LV pressure gradient that again propels blood into the LV.

Detailed explanation-3: -Atria relaxation causes atrial pressure to be lower than ventricular pressure. High ventricular pressure relative to the atria causes the AV valves to close, preventing backflow while the ventricles contract.

Detailed explanation-4: -When the atria fill, pressure in the atria is greater than that of the ventricles, which forces the A-V valves open. 3. Pressure inside atria rises further as they contract, forcing the remaining blood into the ventricles.

Detailed explanation-5: -At the end of the diastole, both atria contract, which propels an additional amount of blood into the ventricles. Systole represents the time during which the left and right ventricles contract and eject blood into the aorta and pulmonary artery, respectively.