tricuspid valve
Chordae tendineae - attached to the valves between both atria and ventricles... these structures are attached to papillary muscles in the bottom of the ventricles. these contract when the valves contract, this keeps the blood from going back up into the atria.
When the atria contract, there is increase in pressure in the atrial chambers. So both bicuspid and tricuspid valves opened up. When both the ventricles contract, both the bicuspid and tricuspid valves get closed. This opens up the aortic and pulmonary valves.
As the ventricles of the heart contract the pressure in the ventricles rises beyond that of the atria. This pressure differential causes the AV valves to shut.
Both AV valves, the bicuspid and tricuspid, (separating the ventricles from the atria) prevent blood from flowing back into the atria when the ventricles contract. Both the semilunar valves (separating the arteries from the ventricles) prevent blood from flowing back from the arteries once it has been pumped out of he ventricles, and thus, out of the heart. The difference is that the AV valves are contracted when they are CLOSED, but the semilunar valves are contracted when OPEN. Otherwise, I can't think of another major job besides preventing backflow.
Papillary muscles are connected to the chordae tendonae on the AV valves. During ventricular systole ( contraction of the ventricles) the papillary muscles contract preventing regurgitation of blood back into the atriums.
There are no valves between the atria. The valves between the atria and ventricles close when the ventricles contract.
semilunar valves
Due to pressure changes in different chambers of the heart. For example, when the atria contract, the bicuspid and tricuspid valves open. They get closed, when the ventricles contract. When the ventricles contract the aortic and pulmonary valves open. Aortic and pulmonary valves close, when the ventricles relax.
As the ventricles of the heart contract the pressure in the ventricles rises beyond that of the atria. This pressure differential causes the AV valves to shut.
There is the contraction of the atria and the contraction of the ventricles. When the atria contract, the AV valves are open, allowing the blood to fall into the ventricles. The AV valves then close, and the ventricles contract, pumping the blood out into the arteries.
open
Chordae tendineae - attached to the valves between both atria and ventricles... these structures are attached to papillary muscles in the bottom of the ventricles. these contract when the valves contract, this keeps the blood from going back up into the atria.
The atrioventricular valves are responsible for preventing blood from flowing back into the atria at the moment the ventricles contract. These valves are situated at the point where the ventricles and atria meet. Atrioventricular valves are two in number; the mitral valve and tricuspid valve.
When the atria contract, there is increase in pressure in the atrial chambers. So both bicuspid and tricuspid valves opened up. When both the ventricles contract, both the bicuspid and tricuspid valves get closed. This opens up the aortic and pulmonary valves.
The atrioventricular valves prevent blood from being pumped back into the atria.
As the ventricles of the heart contract the pressure in the ventricles rises beyond that of the atria. This pressure differential causes the AV valves to shut.
The atrioventricular valves prevent the backflow of blood into the atria when the ventricles are contracting. The semilunar valves prevent backflow from the arteries into the ventricles.