At the start of the cardiac cycle when atrial pressure is higher than ventricular pressure, which process occurs?

At the start of the cardiac cycle when atrial pressure is higher than ventricular pressure, which process occurs?

• A. Passive filling of the ventricles from the atria.
• B. Active ejection from the ventricles.
• C. Atrial contraction without ventricular filling.
• D. Valve prolapse.

Answer: (A)

The key idea is how when the atria are at higher pressure than the ventricles at the start of the cycle, blood flows into the ventricles passively. This opens the atrioventricular valves and allows rapid, passive filling of the ventricles before the atria actively contract. Active ejection happens later, during ventricular systole when ventricular pressure rises above the outflow pressures. Valve prolapse is a faulty event where valves don’t coapt properly during systole. So, at that moment, the ventricles fill passively from the atria.

The key idea is how when the atria are at higher pressure than the ventricles at the start of the cycle, blood flows into the ventricles passively. This opens the atrioventricular valves and allows rapid, passive filling of the ventricles before the atria actively contract. Active ejection happens later, during ventricular systole when ventricular pressure rises above the outflow pressures. Valve prolapse is a faulty event where valves don’t coapt properly during systole. So, at that moment, the ventricles fill passively from the atria.