The right ventricle pumps blood through the pulmonary semilunar valve into the pulmonary trunk, which is just a big vessel that splits to form the left and right pulmonary arteries.
Now, the " DUB" sound — and, just to be clear, I am not talking about dubstep sounds — that's the aortic and pulmonary semilunar valves closing at the start of diastole.
When the ventricle is filled, it contracts, forcing the tricuspid valve to close and forcing the blood through the pulmonary semilunar valve on its way to the lungs.
When this right ventricle contracts, it forces the pulmonary semilunar valve to open, allowing a rush of blood into the pulmonary trunk, which is the large artery that leaves the right ventricle.
The blood continues on its one-way path out of the left ventricle through the aortic semilunar valve, which is the valve that separates the left ventricle and the arteries leading to the body.
At this point, the ventricles are under high pressure, and this high-pressure blood is forced out of the ventricles and into the large arteries leaving the heart through the now-open semilunar valves.
When the ventricles contract, blood in the right ventricle is forced through the pulmonary semilunar valve into the pulmonary artery; at the same time, the tricuspid valve closes to prevent the backward flow of blood into the atrium.