The atrium contracts and blood flows from atrium to ventricle. Which phase is this?

The atrium contracts and blood flows from atrium to ventricle. Which phase is this?

• A. Diastole
• B. Atrial Systole
• C. Isovolumetric Contraction
• D. Ejection

Answer: (B)

When the atria contract and push blood into the ventricles, that phase is atrial systole. In this stage the atria contract, raising atrial pressure and forcing the remaining blood through the open atrioventricular valves into the ventricles, completing ventricular filling. The ventricles are still relaxed during this time, and this event helps set the end-diastolic volume. This phase is distinct from diastole (overall relaxation), isovolumetric contraction (ventricles contract with all valves closed), and ejection (blood is expelled from the ventricles through the semilunar valves).

When the atria contract and push blood into the ventricles, that phase is atrial systole. In this stage the atria contract, raising atrial pressure and forcing the remaining blood through the open atrioventricular valves into the ventricles, completing ventricular filling. The ventricles are still relaxed during this time, and this event helps set the end-diastolic volume. This phase is distinct from diastole (overall relaxation), isovolumetric contraction (ventricles contract with all valves closed), and ejection (blood is expelled from the ventricles through the semilunar valves).