Understanding the Cardiac Cycle

What occurs during atrial systole?

• Atria relax and ventricles contract

• Atria contract and ventricles are relaxed

• Both atria and ventricles contract

• Both atria and ventricles relax

During which stage of the cardiac cycle are both the atria and ventricles relaxed?

• Atrial systole

• Ventricular systole

• Diastole

• Atrial diastole

Why is the maximum pressure similar in both atria?

• Because the atria have the same volume

• Because the atria contract simultaneously

• Because the atria are connected by the same blood vessels

• Because the atria have the same muscle thickness

What produces the first heart sound?

• Closure of the semilunar valves

• Closure of the atrioventricular valves

• Opening of the semilunar valves

• Opening of the atrioventricular valves

What does the QRS complex in an electrocardiogram indicate?

• Excitation of the atria

• Excitation of the ventricles

• Diastole

• Atrial relaxation

What happens when the ventricular pressure exceeds that in the major arteries?

• Atrioventricular valves open

• Semilunar valves open

• Atrioventricular valves close

• Semilunar valves close

What prevents the atrioventricular valves from turning inside out?

• Chordae tendinae and papillary muscles

• High atrial pressure

• Low ventricular pressure

• Semilunar valves

What occurs when ventricular pressure drops below that in the main arteries?

• Atrioventricular valves open

• Semilunar valves open

• Atrioventricular valves close

• Semilunar valves close

What is the role of the papillary muscles during ventricular contraction?

• To open the semilunar valves

• To prevent the atrioventricular valves from inverting

• To close the atrioventricular valves

• To increase atrial pressure

What happens to blood during atrial systole?

• It is ejected from the heart

• It is pushed into the ventricles

• It is returned to the atria

• It is pushed into the major arteries