Heartache

I see, thanks @Prometheus

9 hours ago, Prometheus said:

I don't know the exact electrophysiology behind this but essentially every myocyte has the potential to act as a pacemaker. Generally the pace set by one of these cells is lower the further down the heart it is (so a cell in the atrium would pace faster than a cell in the ventricle).  My understanding is that if the AV node is not receiving an input for any reason it will begin to pace itself, potentially leaving you with two independently (mal)functioning pacemakers. But this is a pathological condition, even if people can survive with milder forms such as atrial fibrillation. Complete heart block would be the worst case before cardiac arrest.

Hmm. Thanks for your response. But, since the two nodes are heavily interconnected and no input is being sent to the AV node, wouldn't that mean that the SA node isn't receiving an input as well? So how would the heart have to independently beating segments if the pacemaking starts from the AV node. 

I could be understanding incorrectly and am slightly confused. Let me know your thoughts--thanks again in advance. 

I need help understanding this: How are the SA node and AV node connected, yet still can function independently?

I know how the two nodes function in unison and how the signal is sent from the AV node--->SA node----> rest of the heart via purkinje fibers, bundle of his, and a network of myocardial muscle tissue. What I really want to understand here is if they can even function independently of each other if they are so interconnected. Any help is much appreciated. 

Thanks in advance