Cardiac Cycle and Heart Sounds

The video explains the cardiac cycle, which consists of atrial systole, ventricular systole, and diastole. Each cycle lasts about 0.8 seconds at rest. During atrial systole, the atria contract to push blood into the ventricles. In ventricular systole, the ventricles contract, causing the semilunar valves to open and blood to be pumped into the pulmonary artery and aorta. The closing of the valves produces the heart sounds 'lub' and 'dub'. In diastole, both the atria and ventricles relax, allowing blood to flow into the atria and ventricles, repeating the cycle.

What is the duration of one cardiac cycle when a person is at rest?

• 1.2 seconds

• 0.5 seconds

• 0.8 seconds

• 1.0 seconds

Which of the following is NOT a stage of the cardiac cycle?

• Atrial systole

• Ventricular systole

• Diastole

• Pulmonary systole

During atrial systole, what happens to the atria?

• They relax

• They contract

• They remain unchanged

• They expand

What is the role of the SA node during atrial systole?

• It closes the semilunar valves

• It opens the tricuspid valve

• It spreads electrical impulses to the atria

• It causes the ventricles to contract

What happens to the semilunar valves during ventricular systole?

• They remain closed

• They open

• They partially open

• They are removed

Which heart sound is produced during ventricular systole?

• Click

• Thump

• Dub

• Lub

During diastole, what happens to the atria and ventricles?

• Atria contract, ventricles relax

• Both relax

• Both contract

• Atria relax, ventricles contract

What prevents the backflow of blood into the ventricles during diastole?

• Open semilunar valves

• Closed semilunar valves

• Open tricuspid valves

• Closed tricuspid valves

Which heart sound is associated with diastole?

• Lub

• Dub

• Thump

• Click

What is the role of the tricuspid and bicuspid valves during diastole?

• They open to allow blood flow into the atria

• They close to prevent blood flow into the ventricles

• They open to allow blood flow into the ventricles

• They remain closed