The phase when the heart is at rest is called ___.

The phase when the heart is at rest is called ___.

• A. Systole
• B. Diastole
• C. Asystole
• D. Cardiac arrest

Answer: (B)

In a normal cardiac cycle, the heart rests during diastole, the relaxation phase between beats. During this time the heart muscle relaxes and the chambers fill with blood; the ventricles fill from the atria as the atrioventricular valves are open and the semilunar valves remain closed. This relaxation period sets up the next contraction, when the ventricles will push blood out to the body and lungs. Systole is the contraction phase, pushing blood out. Asystole means no electrical activity or heartbeat, and cardiac arrest is a dangerous emergency, not a normal phase of the cycle. Therefore, the phase when the heart is at rest is diastole.

In a normal cardiac cycle, the heart rests during diastole, the relaxation phase between beats. During this time the heart muscle relaxes and the chambers fill with blood; the ventricles fill from the atria as the atrioventricular valves are open and the semilunar valves remain closed. This relaxation period sets up the next contraction, when the ventricles will push blood out to the body and lungs. Systole is the contraction phase, pushing blood out. Asystole means no electrical activity or heartbeat, and cardiac arrest is a dangerous emergency, not a normal phase of the cycle. Therefore, the phase when the heart is at rest is diastole.