When you stretch the rubber band, it wants to return back to place. And in the same way, because of this thick layer of smooth muscle, when you stretch the artery, it wants to return back into place. So it expands, but it quickly recoils, returns to place. And this is exactly how the blood actually flows through our arteries. Now, recall that smooth muscle is innervated by our autonomic nervous system. So it's the autonomic nervous system that actually controls the dilation and the contraction of our arteries.