And what that means is they create a network of pipes inside our body that allows the movement of our blood. And that's important because blood carries not only nutrients, electrolytes, minerals and vitamins, but it also carries hormones, waste products and different types of cells to different parts of our body. Now blood vessels come in three different types. We have arteries and we have veins and we also have capillary. So let's begin by focusing on our artery. Now arteries vary in size.