The two atria contract at the same time pumping blood into the 2 ventricles. (tricuspid and bicuspid valves open)
The 2 ventricles contract at the same time pumping blood into the body and lungs. (pulmonary and aortic valves open)
The two atria contract at the same time pumping blood into the 2 ventricles. (tricuspid and bicuspid valves open)
The 2 ventricles contract at the same time pumping blood into the body and lungs. (pulmonary and aortic valves open)