JBL EMT Practice Exam

The phase of the cardiac cycle in which the ventricles fill with blood is called:

1. cardiac output

2. diastole

3. stroke volume

4. systole

The correct answer is: cardiac output

During the cardiac cycle, the ventricles fill with blood during diastole. Diastole is the phase where the heart relaxes and fills with blood. Cardiac output refers to the amount of blood the heart pumps in a minute, calculated by multiplying stroke volume by heart rate. Stroke volume is the amount of blood ejected by the ventricles in one contraction. Systole is the phase of the cardiac cycle when the heart contracts to pump blood out of the chambers. Therefore, the correct answer is diastole because it specifically relates to the filling of the ventricles with blood.