The SL valves close because

Unless there is an influence on the SA node, it will depolarize approximately ________ times a minute.

The SL valves close because

The SL valves close when

The AV valves open when

The AV valves can be opened when the SL valves are closed.

The AV valves can be opened when the SL valves are closed.

Unless there is an influence on the SA node, it will depolarize approximately ________ times a minute.

The SL valves open when

The AV valves open when