And what these gap junctions do is they basically allow the movement of ions through the cells and that allows the propagation of our action potential. So what that means is as our action potential travels through the axon from the autonomic nervous system, it basically innervates these two cells. And these two cells basically undergo that contraction. And that causes the action potential to spread through the other cells that are connected via the gap junction. So that means this entire structure essentially contracts as a whole, as a single unit. And that's why these are called single unit smooth muscles.