Previously we discussed the concept of blood pressure and we said that inside arteries we have a much higher blood pressure than inside our veins. And this is because of a difference in structure of the two different types of blood vessels. Now, blood pressure is not the only measurement that we can use to describe the properties and the behavior of the different types of blood vessels. We can also use a measurement known as compliance to describe the behavior properties of blood vessels. So let's begin by defining what compliance is. So compliance, loosely speaking, describes how easy it is to actually expand a given blood vessel.