The cardiac cycle refers to the sequence of events that takes place from one heart beat to the next. A full understanding of the cardiac cycle requires thorough examination of atrial systole, atrial diastole, ventricular systole, ventricular diastole, atrial and ventricular volume changes during the cycle, electrical events (depolarization and repolarization) of atria and ventricular myocytes, heart sounds associated with turbulent blood flow caused by the closure of semilunar valves, as well as hydrostatic blood pressure changes within the atria, ventricles, and the aorta. Test you basic understanding of the cardiac cycle by taking this simple quiz.
(1) During a typical cardiac cycle under resting conditions, approximately __________ of the volume of blood present in the ventricles just before ventricular contraction (referred to as end-diastolic volume), enters the ventricles as a result of atrial contraction.
(2) During the cardiac cycle, contraction of the left atrium leads to an increase of approximately __________ in the hydrostatic pressure within the left atrium.
(3) During the cardiac cycle, contraction of the right atrium leads to an increase of approximately __________ in the hydrostatic pressure within the right atrium.
(4) During isovolumic contraction (also referred to as isovolumetric contraction) of the left ventricle:
(5) During the cardiac cycle, opening of the atrioventricular valves following ventricular relaxation leads to: