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As is well known, high levels of cholesterol can lead to a buildup of fat in blood vessels, which can lead to them being constricted which makes it more difficult for blood to pass through. In fact, this can end up with the formation of fatty deposits that, if they suddenly break, could result in a clot that causes a heart attack/stroke. Therefore, the resulting buildup of fat because of these high cholesterol levels is highly important.

My question is why do higher levels of cholesterol result in a buildup of fat at all? Why do fatty acids care that there's more cholesterol around? I know cholesterol and fats are both lipids, but beyond that, I don't see the connection.

arara
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  • I assume this isn't a homework question, but you still should have made an attempt to answer this before and shown it here. If the inside of a blood vessel were perfectly smooth, this probably wouldn't occur. But blood slushing along in those blood vessels all day every day do cause some "wear and tear" which is when lipoproteins get involved. – anongoodnurse Mar 18 '19 at 07:08
  • @anongoodnurse I did do some research. Apparently there are cholesterol deposits, where cholesterol is the raw material for the deposits, however, there are other types of deposits and I was unable to find information there. – arara Mar 19 '19 at 03:21
  • The point of my comment is to show your research. Anyone can say they did the research and found nothing helpful. Showing the attempt is what counts. – anongoodnurse Mar 19 '19 at 13:11

1 Answers1

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The phrase "high cholesterol", and the measurement itself is a marker for high levels of a particular lipoprotein, Low density lipoprotein (LDL). Because cholesterol and triglycerides are not soluble in plasma, they are packaged by the liver into soluble particles called lipoproteins. Packaged in lipoproteins, these lipids are transported throughout the body, for use by different organs and tissues. As these lipids are dropped off, the lipoprotein is converted from one form to another, with characteristic biophysical and physiologic properties. The LDL is a late stage of a lipoprotein before reuptake at the liver (and other organs, but mainly the liver) via the LDL receptor. We happen to know that people who have high levels of circulating LDL are at risk for, e.g., cardiovascular disease because of The Framingham Study, and that if you can reduce circulating LDL levels you can decrease the risk for these diseases. The molecular basis of this risk was demonstrated to be, in large part, failure of clearance of LDL particles because of ineffective receptor mediated endocytosis, as described in this wonderful 1986 paper in Science.

From this presentation:

  • Some LDL cholesterol circulating through the bloodstream tends to deposit in the walls of arteries. This process starts as early as childhood or adolescence.
  • White blood cells swallow and try to digest the LDL, possibly in to digest the LDL, possibly in an attempt to protect the blood vessels.
  • In the process, the white blood cells convert the LDL to a toxic (oxidized) form.
  • More white blood cells and other cells migrate to the area, creating steady low steady low-grade inflammation in the artery wall.
  • Over time, more LDL cholesterol and cells collect in the area. The ongoing process creates a bump in the artery wall called a plaque. The plaque is made of cholesterol, cells, and debris.
  • The process tends to continue, growing the plaque and slowly blocking the artery.

There is a good overview of the general physiology here in Robbins The Pathologic Basis of Disease. Chapter 5, Genetic Disorders, reviews the physiology, and the relevance to disease, in the section on Familial Hypercholesterolemia. The review is relevant to hypercholesterolemia in general.

arara
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De Novo
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  • So with more cholesterol, it gets packaged into LDL at a higher rate. So does LDL cause a buildup of fat? How does it do this? Is it the actual raw material of the buildup? – arara Mar 17 '19 at 23:07
  • @Korvexius it turns out to be quite complicated. Inadequate LDL uptake by the liver causes a number of problems. There are some direct effects of high levels of LDL (because they aren't being taken up), and also some indirect effects. Atherosclerosis is in many ways a disease of inflammation as much as it is a disease of lipid accumulation. LDL probably plays a bigger role through initiating an inflammatory process in vessel walls than it does by depositing lipids directly. – De Novo Mar 18 '19 at 06:11
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    @DeNovo - I think an explanation of the genesis of atherosclerosis was what the OP was really asking for. – anongoodnurse Mar 18 '19 at 07:09
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    @anongoodnurse It sounded to me like they were trying to figure out how cholesterol molecules could cause fatty acid deposits. I figured learning what a lipoprotein was (and what exactly "high cholesterol" means) would have been more helpful than reading about foam cells. – De Novo Mar 18 '19 at 07:11
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    @DeNovo - I agree there needed to be a discussion of cholesterol and lipoproteins, but the question was about atherosclerosis - the entire first paragraph, in fact. Also, see the follow-up question. – anongoodnurse Mar 18 '19 at 07:17
  • @anongoodnurse I'd welcome an answer from you with an overview of atherogenesis! I'd have to look through a review myself to make sure i wasn't misremembering anything. – De Novo Mar 18 '19 at 07:20
  • @DeNovo I would also like to see information on the direct cause of fatty acid deposits in your answer if you could. The question is less about atherosclerosis and more about the deposits. – arara Mar 19 '19 at 03:19
  • @Korvexius - Atherosclerosis is about the fatty deposits. Research. – anongoodnurse Mar 19 '19 at 13:10
  • @DeNovo - Apparently you're correct. The OP doesn't want to know about the genesis of atherosclerosis; they want to know how fatty deposition in blood vessels starts. Clearly any answer I wrote would not be helpful. – anongoodnurse Mar 19 '19 at 13:16
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    @anongoodnurse DeNovo is right - I'm well aware atherosclerosis is about fatty deposits and have no idea why you assumed otherwise. But my question directly relates to how those fatty deposits build up, rather than the obvious conclusion that atherosclerosis is an after effect of this buildup. – arara Mar 20 '19 at 04:18