Heart & Cardiac Cycle

Which of the following events is responsible for the "lub" sound in the heart?

• Atrioventricular (AV) valves opening

• Semilunar valves closing

• Atrioventricular (AV) valves closing

• Ventricular diastole begins

During ventricular systole, the pressure in the ventricles:

• Falls below atrial pressure

• Rises above atrial pressure

• Equals the pressure in the atria

• Causes the semilunar valves to open

What causes the "dub" sound in the cardiac cycle?

• Closing of the semilunar valves

• Opening of the atrioventricular valves

• Closing of the atrioventricular valves

• Opening of the semilunar valves

Which phase of the cardiac cycle immediately follows the "lub" sound?

• Atrial systole

• Ventricular diastole

• Ventricular systole

• Isovolumetric relaxation

The semilunar valves prevent backflow of blood in the:

• Atria

• Ventricles

• Aorta

• Pulmonary veins

Which of the following statements is true regarding the cardiac cycle?

• Atrial systole occurs before ventricular systole

• Ventricular diastole occurs before atrial systole

• The "lub" sound occurs during ventricular diastole

• The "dub" sound occurs during atrial systole

During ventricular systole, which of the following valves remain closed?

• Aortic valve

• Pulmonary valve

• Tricuspid valve

• Semilunar valves

What triggers the opening of the semilunar valves during the cardiac cycle?

• Atrial pressure rising above ventricular pressure

• Ventricular pressure falling below atrial pressure

• Ventricular pressure rising above pressure in the arteries

• Ventricular pressure falling below pressure in the veins

The period when both the AV valves and semilunar valves are closed and the ventricles are in diastole is known as:

• Isovolumetric relaxation

• Isovolumetric contraction

• Atrial systole

• Ventricular systole

Which of the following best describes the role of the AV valves during the cardiac cycle?

• They prevent blood from flowing back into the atria during ventricular contraction

• They prevent blood from flowing into the ventricles during atrial contraction

• They open to allow blood flow from the ventricles into the arteries

• They close during atrial systole to prevent backflow into the veins