atriums and ventricles are apart of the four parts of your heart ventricles are on the bottom and atrium's are on the top hope this helped =D
When relaxed, the atria expand, and then the ventricles contract.
Yes, atria contracts before the ventricles.
the difference between the ventricles and the atria is that the ventricles are thicker
ventricles
The Atria and Ventricles are parts of the heart not the blood. The Atria is the upper chambers of the heart and the Ventricles are the lower chambers of the heart.
to force blood to the ventricles
There are no valves between the atria. The valves between the atria and ventricles close when the ventricles contract.
atria are just the receiving chambers, it is the ventricles that actually pump the blood into the pulmonary and systemic circuits
I believe this would be your heart because that is the only time ventricles and atria are brought up.
Assuming you mean the atria and ventricles by "the two heart chambers", the fact that in all species the atria are smaller than the ventricles reflects the fact that the atria receive blood from either the body or the lungs and then pump it into the larger and much stronger ventricles. One-way valves between the atria and ventricles prevent backflow of blood from the ventricles to the atria. The ventricles then pump the blood received from the atria to either the oxygenating organ (i.e. gills or lungs) or the body. The much thicker walls of the ventricles reflect the fact that much greater force is needed to pump the blood throughout the body or to the lungs than is needed to pump the blood from the atria to the ventricles.
No. They are in the organ of the heart
The atria and the ventricles