A single cardiac cycle A lasts 8 seconds when the heart rate

A single cardiac cycle:

A) lasts 8 seconds when the heart rate is 75 beats/minute.

B) forces blood from areas of lower pressure to areas of higher pressure

C) occurs independently of electrical activity in the heart

D) includes all of the events associated with one heart beat

E) refers only to ventricular events

Please explain why the answer is one of those. Thanks

Solution

Answer: (D)

A single cardiac cycle includes all of the events associated with one heart beat.

Cardiac cycle in general refers to all the activities of the heart in one heartbeat. This includes contraction (systole) and relaxation (diastole) of both the atria and the ventricles.

The other options do not properly explain the cardiac cycle. (The time period of one cardiac cycle is 0.8 seconds when the heart rate is 75/minute. Ventricular contractions supplies blood to the arteries, from a region of high pressure to a region of low pressure. Electrical impulse from the sino-atrial node (SAN) initiates cardiac cycle.)