Final answer:
The statement is false; at the end of ventricular diastole, the ventricles are filled with approximately 70-80 percent of their capacity due to blood inflow, with atrial contraction further filling them to nearly full capacity, known as the end diastolic volume (EDV).
Step-by-step explanation:
The statement that the ventricles are almost empty at the end of ventricular diastole is false. During the cardiac cycle, ventricular diastole is split into two phases: early and late. In the early diastolic phase, after the ventricles have contracted during systole, the pressure within the ventricles begins to drop, but the volume remains constant due to closed semilunar and atrioventricular valves. This is known as the isovolumic ventricular relaxation phase. Later as diastole progresses, pressure in the ventricles falls below that in the atria leading to the opening of atrioventricular valves and allowing blood to flow from the atria into the ventricles. At the end of ventricular diastole, the ventricles are filled with approximately 70-80 percent of their capacity due to this inflow of blood hence the term 'diastole' is often referred to as the filling stage.
Atrial contraction then tops up the remaining volume, contributing an additional 20-30 percent to ensure the ventricles are almost full, not almost empty, at the end of ventricular diastole. This full volume of blood in the ventricles is referred to as the end diastolic volume (EDV) or preload, significant in determining the stroke volume during the subsequent ventricular systole.