Question

Choose the correct sequence of events in the cardiac cycle:
I. Ventricular systole
II. Blood reaches ventricles
III. A-V valves closes
IV. Atrial systole
V. Semilunar valve closes
VI. Blood goes to major arteries
VII. Semilunar valve opens
VII. Ventricular diastole

• A. IV→II→I→III→VII→VI→VIII→V
• B. I→II→III→IV→V→VI→VII→VIII
• C. IV→II→VIII→VI→VII→IV→V→III
• D. I→II→III→IV→V→VI→VII→VIII

Answer 1

The correct option is A IV→II→I→III→VII→VI→VIII→V

A cardiac cycle begins has the following steps:
IV. Atrial systole: contraction of atrium

II. Blood reaches ventricles: From the atrium, majority of the blood passively flows to ventricles but the remaining some portion is pumped to the ventricles during atrial systole.

I. Ventricular systole: contraction of ventricle.

III. A-V valves closes: As the pressure is increasing in the ventricles, the valve closes to prevent the back flow of the blood to the atrium.

VII. Semilunar valve opens: Due to ventricular contraction, the pressure increases to a point where it exceeds the aortic pressure resulting in the opening of both the semilunar valves.
VI. Blood goes to major arteries.

VIII. Ventricular diastole: Fall in ventricular pressure.

V. Semilunar valve closes: It happens to prevent the back flow of the blood from the arteries as the pressure is falling in the ventricles.