Blood vessel diseases
Arteriosclerosis, arteriolosclerosis, and atherosclerosis Learn the difference between Arteriosclerosis, Arteriolosclerosis, and Atherosclerosis! Rishi is a pediatric infectious disease physician and works at Khan Academy.
Arteriosclerosis, arteriolosclerosis, and atherosclerosis
- So there are a few words that get thrown around. When I was going through and learning them I was always confused.
- I thought I would go and talk about them right now.
- The first word is Arteriosclerosis. I'm going to underline the one O here.
- Very similar to this word is the word Arterioloscerlosis, with an extra L and O and everything else is the same.
- The first thing I always wondered was are these the same word that someone just misspelled. But actually that is not the case.
- This is two separate words for two separate things.
- A third word is Atherosclerosis. I used to wonder the same thing about this word.
- Is this just another way to spell it? Maybe the British spelling or something like that? But actually it is another word that is different in meaning as well.
- So these three words often get confused for one another, and sometimes you will see that they are referred to as the same thing.
- But there are some subtle differences I want to talk about.
- So lets start with the first two words: Arterio and Arteriolo sclerosis.
- And these basically get to the question, answering the question, of "What is happening?"
- And the process of arteriosclerosis and arteriolosclerosis is that you basically have stiffening of blood vessels.
- So if you have a normal vessel. I'll draw it in red like a rubber hose. This is a very soft flexible vessel.
- And over time if it becomes stiff like a lead pipe, then you have something like this. A very firm vessel.
- So same size, but basically the walls are becoming very very stiff.
- And arteriolosclerosis is kind of the same process.
- So far I have not convinced you that there is any difference right? Same basic process.
- So you are probably left wondering "Well then what is the difference?"
- Well the difference is that arteriosclerosis is happening in the large arteries and middle sized arteries. So large and middle sized arteries.
- And you remember we divided up the arteries into the large and middle, and on the other side we said what about the small arteries and arterioles.
- That is over here.
- So basically if this process is happening in the large and middle sized arteries we would call it arteriosclerosis, with a single O.
- But if it is happening in the small arteries and arterioles, we would call the same process arteriolosclerosis. So thats the key difference: Where is it happening.
- Now in terms of answering the question of what, this is the process but you have to ask yourself "Why does that matter? Why does it matter if something is going from soft to firm?"
- I'm going to draw a spectrum for you. On this side we have the word Not, and here you have Very. These are referring to compliance.
- Try to remember back to what we said about compliance. And that's whether or not a vessel can stretch, almost like stretchability.
- If you think about what would be very stretchable or very compliant, we've got veins. So that would be over here, a vein.
- Arteries are over here. They're not so compliant. They are not completely stiff, but compared to veins they are not very compliant.
- So they have much lower compliance than veins.
- A lead pipe would be right here. Basically right next to Not. This would be a lead pipe.
- When we talk about arteriosclerosis or arteriolosclerosis as something that is soft going to something that is firm, we are really talking about the artery moving from where it is on the compliance spectrum over here towards not too compliant at all.
- So really we are talking about losing compliance. Let me right that. Losing compliance.
- That's a really important word. And that's really what we are talking about. Losing compliance.
- Now how do we get to a point where we are losing compliance. How does that happen exactly?
- Well that's another question. That's the question of How? How does this happen?
- There we can talk about atherosclerosis.
- Atherosclerosis is a process. I can even draw it out for you very quickly.
- Lets say this is a blood vessel, an artery. I'll draw two layers for its wall.
- Although we know there is actually three layers I'm just trying to make it simple by drawing to layers just to show that there is a thickness.
- Let's say that you have some fat deposit here and maybe one over here.
- Over time we know that this is going to cause some blockage of the vessel.
- But also in addition to losing space in the lumen, this is the lumen. In addition to losing space in the lumen you also have some calcification and some fibrous tissue starts laying down here.
- So this wall, instead of being nice and soft and red, I'm going to draw it as very firm and white. Very firm.
- So this part of the wall and maybe even this part of the wall becomes very non-compliant. They lose compliance here.
- So these parts of the walls are very firm. They are not going to stretch out very easily.
- That's atherosclerosis.
- The reason I listed it under this section here, if I can divide it in half, is that most often (not always, but most often), atherosclerosis is happening in the larger or middle sized arteries.
- It doesn't happen as often in the small arteries and arterioles. So its happening more often in the large and middle arteries.
- So it's going to cause arterioslcerosis. So atherosclerosis is the How, and arteriosclerosis is the What for the large and middle sized arteries.
- Now lets shift over to the small arteries and arterioles.
- So if I just told you that atherosclerosis doesn't happen too often in the small arteries, then how in the world does arteriolosclerosis happen?
- Again, arteriolo with an olo. How does that happen?
- Let me right out for you a couple words. These are words that you might come across.
- Hyaline and Hyperplastic. So these are just names for a process. Again, these are answering the question of How does arteriolosclerosis happen.
- Well, it happens through hyaline or hyperplastic arteriolosclerosis. So the word appears again here.
- And this, let draw it as I did before.
- We have a vessel. Instead of having a plaque, which is what I drew before, in my vessel this time I'm going to talk about blood pressure being really high.
- So here we are talking about things like, let me right over here high blood pressure or diabetes.
- So in situations like this you can have lots and lots of pressure pushing out of the vessel.
- These are my little arrows talking about blood pressure.
- As the pressure is pushing out, what happens is that some of the proteins from inside the vessel get pushed out into the vessel walls.
- That vessel wall gets loaded with protein, extra protein that doesn't usually belong there.
- It's got little protein everywhere because it's being pushed by all that high pressure.
- Over time having all this protein here I'm drawing in pink is going to cause these vessels to start losing compliance.
- So all the way around actually they will start losing compliance.
- And again this is not how it ALWAYS happens, but this is just an example of how it could happen.
- You could lose compliance this way. So this is a great example of something that was soft is becoming very firm over time because of blood pressure related issues.
- Alright we will pick up there next time.
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