What is pulmonary hypertension?

- [Voiceover] Hypertension means exactly the same thing as high blood pressure. This can be a disease on its own. So when people have high blood pressure, we can say they're hypertensive or they have hypertension. Now, pulmonary is a word, every time you see this, it's going to be referring to our lungs. So pulmonary hypertension is literally high blood pressure in the lungs. And you might be thinking, what do you mean? How can there be high blood pressure in what seems like a sac of air, right, or in our lungs? But in fact, the lungs are a very important part of the circulatory system for our blood. Let's look at really quickly what the heart and lungs do. And I drew this blue person here to show you that blood coming from the body returning to the heart is blue or low in oxygen. We use blue to represent that because the muscles have extracted the oxygen out of the blood and used it. So we have our heart here with its four chambers. Now, this is going to be the right side. This is going to be the left. In medicine, left and right is usually flipped, as the person is facing you, so their right is your left. All right, we have right atrium, receiving chamber, right ventricle, from here it goes to the lungs. Left atrium, left ventricle. So the blood comes in here first, blue blood from the body goes into the right ventricle. And from here it goes to the lungs. Let's draw some lungs really quickly, windpipes, into smaller airways, and our lungs are these two big structures, like that. And indeed, it looks like two sacs of air. But the truth is with each of these as they start branching off with all the airways, the blood vessel, blood supply actually follows the same pattern, the same path as the airway, so that we get a very good system that interfaces between the blood and the air. And the purpose of that is to get oxygen into the blood. Now, I'm using red here to draw this just because blood we usually think of as red. But remember that it comes in as deoxygenated blood and leaves as oxygenated. Just to blow that up for you, this is our alveolus or the smallest unit in the lungs and air sac. The blood supply would run just along it. Blue first without oxygen. And as the oxygen enters into the blood, it turns red, so the blood supply leaving the lungs is red. All right, so we got oxygenated it. And we need to return to the heart. Now we're red blood with oxygen to the left atrium, goes into the left ventricle, and from there it goes out the aorta to the body and now we have a red person. So roughly this is the path of the blood in our body. So if we think of this as almost a circuit where there are many stops along the way that liquid has to flow through, let me see if I can make this make sense. So if we have our body here that is giving blood to the heart, this is our heart, we have our lungs, and returning to the rest of the body, so we need one more unit here into our body. Of course, this is connected. It's in a loop. So the pulmonary hypertension, we have the lungs are clamped down. Hypertension means there's a lot of resistance in this area of the circuit. So basically, it's hard for liquid to flow through. And as you can imagine what would happen is that would have a lot of back up into these parts of the circuit. Because it's hard to get blood through, then we back up. And then going forward, we have not enough because the blood is trapped here. It's bottlenecked.