The arterios empty out that blood directly into our capillaries. And capillaries are these really specialized blood vessels that are very thin. In fact, they're only a single cell layer thick. And that means they are not actually built to withstand any high pressure like our arteries are built. And in fact, because within the capillaries we have an exchange of nutrients and waste products taking place. That basically means is for that exchange to take place efficiently the flow of the blood within the capillaries has to be relatively slow.