3. Electrical conduction through the heart

The heart contracts in a _ sequence because electrical activity travels through a _ and spreads between myocardial cells through _.

coordinated, defined pathway, gap junctions

Where does the SA node initiate the action potential?

The right atrium

What happens after the action potential is initiated?

The signal spreads through the atria, producing atrial depolarization and atrial contraction

What does the AV node do?

Receives the signal and delays transmission, which give the ventricles time to fill up before they contract

Where do the signals travel after the delay?

the AV bundle, bundle branches, and Purkinje fibers

How does ventricular excitation spread? What does this mean for ventricular contraction?

From the apex upward, ejects blood towards the pulmonary aorta and aorta

How does ventricular depolarization travel.

Opposite, to the apex

Which node is the dominate pacemaker? Why?

SA because it reaches threshold the fastest, slower pacemakers can take over if damaged

What are gap junctions?

electrical connections between cardiac cells, they allow current to spread so the myocardium behaves as a coordinated network