Health and medicine
- What is hypertension?
- Intro to hypertension (Pressure, flow, and resistance)
- Intro to hypertension (systolic and diastolic blood pressure)
- Stages of hypertension
- Hypertension types and causes
- Primary hypertension
- Secondary hypertension
- Hypertension effects on the blood vessels
- Hypertension and blood vessel damage
- Hypertension effects on the heart
- Hypertension and heart damage
- Complications of hypertension
- Hypertensive crisis
- Diagnosis of hypertension
- Treatment of hypertension
- 4 lifestyle changes to help manage hypertension
Learn 2 major heart problems that hypertension can cause. Rishi is a pediatric infectious disease physician and works at Khan Academy. Created by Rishi Desai.
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- What actually causes the heart muscle to grow thicker? And why would it grow thicker without growing sufficient blood vessels to supply it?(5 votes)
- The heart is, as you say, a muscle. It grows by the same principles as skeletal muscle do. So when the workload increases, the muscle compensate by hyperthophy - growing in volume. This happens when you work out as a physiological response. However, this can also happen when the workload increases pathological - caused by a disease. For example aortic valve stenosis. Over time, if the workload is too big, this will exhaust the heart and lead to heart failure.(10 votes)
- At the end of the video you said that the heart can't keep up with the force required, thus it pumps out 5 liters vs. the necessary/ (total volume) 6 Liters. Would this result in immediate heart failure? Or is it more like, over time the heart tries to keep up and then shuts off function after a number of (days, months, years) of inadequate pumping?
Also what happens to the extra Liter that isn't pumped? Does it become something like stagnant blood?(4 votes)
- A human have on average 5l of blood, varying between men and women amongst other factors. This blood is continuosly circulated by the heart. Simplified, the job of the blood is to transport oxygen to tissues, and waste products like carbon dioxide from tissues. So saying that you need 6l of blood, it means 6l of oxygenated blood per minute. But if the heart is exhausted or weak, it can't deliver the demanded amount of blood. Either it can't beat fast enough or contract hard enough. It can only deliver 5l per minute. So the body doesn't get the oxygen needed, which, if untreated, is disasterous. This can happen immediate if the heart is damaged by an infarction, or over time if the patient have for example high blood pressure.(4 votes)
- @1:20The Aorta sees the highest pressure as the blood leaves the heart. Is this a very common area for aneurysms and other failures because of this fact?(2 votes)
- Do not think aneurysm happen only where there is a large pressure. Not necessarily. Aneurysms can also happen in the brain, which depending upon area affected, have their respective names. To name a few there is epidural and subdural hematoma.(3 votes)
- Could someone please specify the types of resistance in blood vessels that (forces the heart to pump out blood at an increased pace) or refer a video pertaining to that information?(2 votes)
- arteries have a narrower lumen as compared to veins which is why they have a higher pressure. now when we perform a vigorous activity like exercise the blood required to provide energy to the body to perform the activity is more. Due to this the heart pumps more blood at an increased rate.
Does this answer ur question?(3 votes)
- How does hypertension effect the walls of the myocardium?(2 votes)
- It leads to hypertrophy, i.e. enlargement of the muscle cells that make up the myocardium.
Think of water in your mouth that you empty through a straw. If you have a wide straw, it will be very easy. Imagine a narrow straw. You'll have to push hard for the water to flow through the straw. This is because the narrower straw has higher <b> resistance </b>. This is essentially what happens in hypertension. The myocardium thickens so that the muscles are strong enough to push blood through the systemic circulation. This is helpful in the beginning, but as the muscle becomes bigger and bigger, it leads to problems. That's another story though.(2 votes)
- what is Mean arterial pressure ?(2 votes)
- It is the average blood pressure over the course of a heartbeat. Think of it as the average amount of pressure in a tube. In medicine, the MAP is important for tissue perfusion. If the MAP is below 60, we generally feel that the tissues are not being perfused well, and this can lead to ischemia.(2 votes)
So we were talking in a previous video about hypertension and the damage that it causes on the body. And what I'd like to do is pick up where we left off and finish that conversation. And we had kind of divided things up into receiving high blood pressures and generating high blood pressures. And receiving high pressure-- really, that means the vessels, right? That's where the pressure is going to be seen. And so the vessels can get damaged. And we talked about some of the different ways that that can happen. And in fact, there are the larger arteries and also the smaller arteries. But now, let's focus our attention on generating high pressures. Because this might be less intuitive, but actually making the pressure go so high is not an easy thing to do. And it's actually a very challenging task for the heart to accomplish. And in trying to figure it out, sometimes the heart can run into troubles. So there was an equation, and that equation was delta P equals Q times R. And I thought we had put some words to this equation. So the idea that delta P-- that's basically saying the arterial pressure minus the venous pressure. So if you have blood and it's exiting here, and that's got a certain pressure on it. And as it enters again on the other side into the atrium, it's got a pressure on the venous side. So we're saying that the pressure leaving in the arteries minus the pressure returning in the veins is what's going to help you take a certain flow of blood, Q, past the resistance in the vessels. So that's a way of thinking about it. And specifically-- let me actually draw out some of this resistance. You have, of course, resistance once it gets into the arteries. And so you've got some, R, resistance there. Then you've got more resistance once you get into the arterioles. In fact, I'm going to triple underline that one because there's lots of resistance in the arterioles. And then you've got resistance in the capillaries, and you've got resistance in the veins. And then you've got the blood returning into the venous side. So there's resistance in the circulatory system. And there's a flow of blood that you're actually trying to move around, right? So anything, anything at all, that increases the resistance or increases the flow is going to force the amount of pressure you have to put in on the arterial side to go up. And now if I draw it out, you'll see even more clearly why this is a problem. So if you have, let's say, the left ventricle, and I'll leave a little space for the valves. And this is the chamber of the heart that's doing the pumping now. And it's pumping the blood out into the aorta. This is the aorta. And this is another valve. And this valve is called the aortic valve-- pretty easy to remember name, aortic valve. And it separates the aorta from the left ventricle-- LV for Left Ventricle. So the left ventricle is basically going to have to try to get blood through this door, through this valve. And the way to do that is to apply a force to that blood and force it through that door. Now, the aortic valve has a certain area. And so if you remember, any time you have a force over an area-- I'll write that over here-- anytime you have a force over an area, you have a pressure. And in this case, that is the arterial pressure. So when I talk about arterial pressure, I'm actually talking about the force that the left ventricle generates on that aortic valve, that area of aortic valve. So now, think about it. If you have, let's say, more resistance. Let's say there's lots and lots of resistance in the vessels, so that all these numbers are slowly going up, up, up. Well, that's going to cause the overall resistance to go up, and now the left ventricle has to put more force. Or you could say, what if you have larger flow? You actually have a larger volume of blood you're trying to move around. Again, the aortic pressure is going to have to go up. So the way that the left ventricle accomplishes this or tries to accomplish this is by basically building more muscle. So this is one strategy. It'll say, OK, well, if I need to generate more force, why not generate more muscle? So this becomes very muscular in here. If you actually look at a heart that has had high pressures over the years, oftentimes you have what's called left ventricular hypertrophy. So on the surface, this sounds great, right? Left ventricular hypertrophy sounds like you're making the muscle of the heart stronger. And that sounds like a good thing. You know, that's certainly why I go to the gym. I want my muscles to get bigger. So it's confusing, then, to hear that that's not a good thing, and here's why. So now, imagine you have all this muscle, and you're feeling really good. But then I tell you that, well, this muscle's using more oxygen. So it's using more oxygen. But you notice I didn't draw any new blood vessels yet. So there are no new blood vessels getting oxygen to this muscle. But the muscle is definitely using a lot of energy, and it needs a lot of oxygen. And so what happens is that you have areas where blood is basically able to get to those areas and other areas where blood is not able to get there. And where the blood is unable to get enough oxygen to that heart muscle, you could have a heart attack or a myocardial infarction. So left ventricular hypertrophy is a way of compensating for needing more force. But it comes with a little bit of a risk because now you might have a risk of an MI or Myocardial Infarction. The other possibility is that the left heart doesn't compensate, and you have what's called left heart failure. And what that basically means is that the left heart says, you know what, I can't generate the pressures that are being required to move all that blood around, and so I won't. I won't generate those pressures. I'll do the best I can, and maybe I can't move, let's say, six liters of blood around the body, but I can do 5 liters or 5 and 1/2 liters. So it'll try to do what it can to move as much blood as possible, but it is essentially not compensating completely. And that's why you sometimes see people with heart failure after having years and years of high blood pressure. Their heart simply can't keep up. And so you experience heart failure.