What changes, compared to fish, have occurred in the circulatory system of amphibians?

Fish are characterized by the presence of a heart with two sections and a single circle of blood circulation.
The circulatory system in amphibians is more complex. In connection with the possibility of going on land, with the appearance of lungs for breathing, another circle of blood circulation appeared. Now there is a large and small circles of blood circulation. Their heart consists of three sections: two atria and one ventricle, and there is a septum in the ventricle, but it is incomplete, therefore the blood in amphibians is mixed. In this regard, the metabolism of amphibians is at a low level. It is also worth noting that their activity depends on the ambient temperature, since they are cold-blooded.