Well, if we notice, if we take a look at the following diagram, we have the SA node and we have another type of node known as the AV node, which stands for the atrioventricular node. Now the atrio ventricular node is also a collection of specialized cardiac muscle cells that is located inside the interatrial septum of our heart. That's basically the wall that separates the two atrium of the heart. So this is found between the atria and between the ventricles of our heart. Now what this AV node does is it does two things. Firstly, once it actually receives that action potential from the essay node, it delays that action potential by about zero point twelve of a second.