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. Now, single unit smooth muscles are found in places like the uterus. Why well because when the woman is given birth the uterus has to contract as a single unit and that's why all the smooth muscles are arranged into this single unit smooth muscle arrangement. Now other places where we find this type of arrangement is the stomach, the small intestinal bladder, as well as small arteries and veins.