13.3-13.4

What is the first event of the cardiac cycle as described in the learning material?

• The ventricles contract

• The entire heart relaxes

• The atria contract

• The ventricles relax

During the cardiac cycle, what happens immediately after the atria contract?

• The atria relax and the ventricles contract

• The ventricles relax

• The entire heart relaxes

• The atria contract again

What is referred to as ventricular diastole?

• The contraction of the ventricles

• The relaxation of the atria

• The relaxation of the ventricles

• The entire heart contracting

What causes the pressure within the heart chambers to rise and fall?

• A) The contraction and relaxation of the ventricles only

• B) The contraction and relaxation of atria and ventricles

• C) The relaxation of the atria only

• D) The contraction of the ventricles only

What happens to the AV valves when the ventricles contract and pressure inside them increases?

• The AV valves open

• The AV valves close

• The AV valves disappear

• The AV valves expand

What role do the papillary muscles play during the contraction of the ventricles?

• They relax the ventricles

• They open the AV valves

• They contract and pull on chordae tendineae

• They increase the pressure in the ventricles

What occurs when the ventricular pressure is lower than the blood pressure in the aorta and pulmonary trunk?

• The AV valves open

• The semilunar valves open

• The semilunar valves close

• The AV valves close

Which event marks the beginning of the next cardiac cycle?

• Ventricular pressure being higher than atrial pressure

• AV valves closing

• AV valves opening when ventricular pressure is lower than atrial pressure

• Semilunar valves opening

What causes the heart sounds in humans?

• Blood pressure

• Valve vibrations

• Muscle contractions

• Electrical impulses

How can normal heart sounds be described?

• Click-clack

• Whoosh-whoosh

• Lubb-dupp

• Tick-tock