 Now there are a couple of concepts that you might run into in a clinical setting that are related to blood pressure and one of them is this concept of pulse pressure. Pulse pressure is essentially the systolic pressure minus diastolic and it's significant because the difference between those can give you information about the compliance of your vessels. If your vessels do not stretch well enough or are abnormally unstretchy, then you're going to have a pulse pressure that's out of normal range. And that can tell you that that's going to affect cardiac function and health of your overall system. The other concept that, again, in general, the other concept is the mean arterial pressure. Mean arterial pressure is aiming to estimate the amount of pressure in your vessels over several heart beats. And the argument is that mean arterial pressure is what is actually regulated from a homeostatic perspective by your own body. So your body doesn't respond to the one beat of the heart. Your body responds to this concept of mean arterial pressure. So let me tell you what that is. Mean arterial pressure is diastolic pressure plus one-third of pulse pressure, which means systolic minus diastolic pressure plus diastolic. And you might be looking at that going like, why is diastolic more? And it's because over time, your heart is in diastole much longer than it is in systole. And so this number, the mean arterial pressure, actually lets you accommodate for that amount of time. Does that make sense? When you take your blood pressure using your sphigmomantometer, you're estimating aortic pressure in a moment, in a heartbeat. When you consider the concept of mean arterial pressure, you're looking at a bigger picture. You're looking at kind of an average over a period of time, over several heart beats. You can understand that these numbers are going to be affected by cardiac output and they're going to be affected by resistance, which is why they have clinical significance when you're looking at cardiovascular health. Now, the entire lecture was supposed to be talking about capillary exchange and we're almost there. In the next section, we're going to talk about capillaries in general and again, blood pressure is absolutely a function of capillary exchange. So make sure you're comfortable up to this point before moving onward.