Cholesterol Metabolism, LDL, HDL and other Lipoproteins, Animation
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- Опубликовано: 30 апр 2018
- (USMLE topics) The science behind the GOOD and BAD cholesterol. Cholesterol transport and pathways, drugs used for treatment of atherosclerosis.
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Despite having a BAD reputation as a high-risk factor for cardiovascular diseases, cholesterol is an ESSENTIAL component of all animal cells. It is an INTEGRAL part of the cell membrane, providing membrane FLUIDITY and participating in a number of cellular processes. Cholesterol also serves as a PRECURSOR for production of bile, steroid hormones, and vitamin D. While the body can obtain cholesterol from food, many cells SYNTHESIZE their own ENDOGENOUS cholesterol. Cellular production of cholesterol is under NEGATIVE FEEDBACK control. LOW levels of intracellular cholesterol INDUCE its own production, while HIGH cholesterol levels INHIBIT it.
Cholesterol, together with other lipids, is transported in blood plasma within large particles known as LIPOPROTEINS. A lipoprotein is an assembly of lipids and proteins. Lipoproteins are classified based on their DENSITY. Because lipids are LIGHTER than proteins, particles that contain MORE lipids are LARGER in size but have LOWER density. Different types of lipoproteins have different sets of proteins on their surface. These proteins serve as “ADDRESS tags”, determining the DESTINATION, and hence FUNCTION, of each lipoprotein. For example, LOW-density lipoprotein, LDL, carries cholesterol FROM the liver to other tissues, while HIGH-density lipoprotein, HDL, RETURNS excess cholesterol TO the liver.
Major events in cholesterol metabolism include:
- Dietary cholesterol ABSORBED in the intestine and carried in chylomicron to the liver.
- The liver PACKAGES its cholesterol pool - a combination of endogenous and dietary - together with triglycerides, another type of lipid, into particles of VERY-LOW-density lipoprotein, VLDL.
- VLDL travels in bloodstream to other organs. During circulation, muscle and adipose tissues EXTRACT triglycerides from VLDL, turning it into LOW-density lipoprotein, LDL.
- Peripheral cells TAKE UP LDL by endocytosis, using LDL receptor. Cholesterol is used in cell membrane and other functions.
- EXCESS cholesterol is exported from the cells and delivered to HIGH-density lipoprotein, HDL, to be RETURNED to the liver in a process called REVERSE cholesterol transport.
- The liver uses cholesterol to produce BILE; bile is secreted to the intestine, where it helps break down fats. Part of this bile is EXCRETED in feces; the rest is RECYCLED back to the liver.
LDL has the highest cholesterol content and is the MAJOR carrier of cholesterol in the blood. High levels of LDL in the blood are associated with cholesterol plaque build-up and cardiovascular diseases such as heart attacks and strokes. For this reason, LDL is known as “BAD” cholesterol. On the other hand, HDL is called “GOOD” cholesterol, because it REMOVES EXCESS cholesterol from tissues and bloodstream.
Common drugs used to LOWER cholesterol include: INHIBITORS of endogenous cholesterol PRODUCTION; INHIBITORS of intestinal cholesterol ABSORPTION; and INHIBITORS of bile reuptake.
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Explained to me in 4 minutes what my lecturers couldn't explain me to in 1 hour. Thank you
LOL what are you studying?
Danny Williams
It’s very limitedly informative but good for premed beginners tho (not even enough for premed)
@@xufenghuang1634 yeah ! But for example, i will be working on lipid metabolism disorders and I am here to get some info before that
In harper it is given nicely....and after that you can see Lippincott for revision too
Very true
Best video in 4 mins. Let's show some love here.
The BEST explanation. All you gotta do is brush up on some notes if you haven't already and you're good. Or can also serve as a wonderful review to put everything together. Amazing!
It should be mentioned too, that LDL is not a cholesterol at all, but a cholesterol "transporter". We just call it LDL "cholesterol" for convenience but, it's not really correct.
Absolutely.....
it is said in the beggining of the video, that cholesterol is transported in lipoprotein particles and she talks about “low density lipoprotein - LDL” and not LDL cholesterol
@@nikoletavassova3927 Hmmm, I must have missed that part. Thank's for pointing that out.
Also listen at 3:05 where it’s stated that LDL is known as bad cholesterol
@@michaell132 Yeah, I've always hated that term "bad" cholesterol. No such thing as bad cholesterol, just two different kinds of cholesterol. LDL is not necessarily "bad". I much prefer the more descriptive term of "small dense particles" and large. The large ones are harmless and just bounce around in the bloodstrream. Those small ones though, are the bad ones that lodge on artery walls, Atherosclerosis.
Hands down the best explanation with best visuals I've seen yet! Thank you so much for sharing!
What an incredible, clear and concise run through of lipid transport. The best I've seen. Thank you
you're the real MVP! short & simple way to review! THANKS!
Learned something new about the difference between HDL and LDL. Thanks!
thank you for explaining this biochemistry and pharmacology stuff in such simple way!
content that is compact and easy to understand. I Stan
Amazing video. Thank you so much.
The Video I've been looking for. Great job
Such explanations are useful to all medical professionals& I expect more such useful information
5 hours lectures in 3min you saved my semester!!
This is amazing and so helpful!!!!
Great VDO! Highly knowledgable was that stuff! 🤩
I love that the video that was the easiest and clearst to understand was narrated by a woman :)
Thank you so much Vicky!!
Hi, just wondering what your thoughts are on the different types of LDL - pattern A and pattern B which are increased in different diets? Also, thank you simplifying all these processes. Very helpful.
Good summary of all the processes involved in Lipid transport ...
just wow! soo simplified! thank you :)
Very well explained! Thank you!
Awesome Video! Had a much clearer concept about LDL & HDL now. Thank you!
Kudos on an awesome informative video. Thanks!!
this is amazing! thank you for this video!!!
Oh my god. This video just packed together an entire day of gibberish so it made sense. Its SO FUCKING GOOD.
What you're doing is excellent. Thank you 💕.
Hat's off to u champ👏
Great explanation 👍
Thank you for explaining cholesterol metabolism
It gives a fundamental knowledge about lipid metabolism to comman men and students. Thankyou very much with appreciations.
Absolutely great!
crazy how much you can learn in 4 minutes, while ive been reading for hours not getting it
Excellent video. It helped me a lot. Thank you. 🙂
You guys are awesome!! Keep it up with the good work.
It's amazing video, thank you so much really
Omg thank-you i got confused, this is very helpful
Informative and Straight forward
really good explanation, thanks
Thanks for the video it's very helpful ^^
Short and excellent explanation... thanks for the video 😊
Great work!
this is amazing, this vid is SO GOOD
Very clearly explained...🥰
Amazing video thanks very much
Very helpful, thanks.
best explained........thanks a lottt
Its is so helpful, thanks!
Love how you explained this. Thank you
Glad you enjoyed it!
@MrBilld75 Agreed. I'm glad to see more people are catching up on that distinction. It is important to note that unbiased evidence indicates that LDL is "associative" in atherosclerotic plaque formation as opposed to being "causative". There's a huge difference between the two particularly with regard to prevention and treatment. We are still looking into this but the current evidence indicates that LDL can get damaged by glycation, oxidation and inflammation as a result of too much sugar/refined carbs intake, plant sterols (yes..in spite of the fact that it's ironically used to lower supposedly "bad" cholesterol) and a state of systemic inflammation (from the progression of insulin resistance for e.g.). I'm on the train right now so I can't type much...I'll try and elaborate on this another time.
Damaged LDL are mostly of type B (dense). For example, one mechanism causing issues is the fact that the apoprotein B100 on LDL get damaged enough so that they can't be recognised and reabsorbed by the liver receptors for recycling. So they end up pooling in the circulation hence promoting adhesion to the vascular endothelium. Inflammation also makes the endothelium prone to that phenomenon. LDL is also a repair molecule so it will also migrate (by transcytosis using ATP) to sites of inflammation in an attempt to repair thus further exacerbating plaque formation over time as this process is repeated. Macrophages also try to engulf those inflammatory LDL complex resulting in foam cells and this also triggers more cytokines release (pro inflammatory). So you can see how this cascade can result in more plaque formation over time. Too long to elaborate on but hope that quick summary helps.
Great explanation👍👍👍
to the point, simple, clear. G-d sent! tysm!
Amazing and easy revision
Great explanation.. Keep up the good work.. 👍👍👍👍
oh my gosh. Thank youuuuu!
WOW so good, it was so helpful
Nice video, great lecture, understand able.
Perfect thank you so much
A huge love form India...🙏
Welldone. Good job.Hat off
Good explanation
Good work👍👍👍
Thank you so much
So helpful 🥺♥️ thank U to make the Arabic translateor
It might be a bit late to ask, but Im curious whether dietary cholesterol generally is processed more into LDL, since there was a lot of controversy regarding dietary cholesterols.
very cool video, got myself a note on my whiteboard from that.
Wow! Thank you! Was so well explained ,thank you
You're very welcome!
Excellent
Thx that was v. Helpful
Iife saver thank you so much!😘
Thank you for the lovely video, very helpful
You are so welcome!
Wonderful. ,,... thx
wow, for me am highly educated by this info thanks
Glad to hear!
thank's from Fac of Medecin of Algeria
Best explanation so for.
Fantastic explanations. Thanks!
Glad you enjoyed it!
Just wooooow
Thanks ❤❤❤❤❤❤
Awesome 👍 saved me 🙏
Very good. It would be even more helpful if intracellular processing of LDL cholesterol was included. One point would be to explain how cholesterol is exported from lysosomes. How many pathways are there? One pathway is via the lysosomal membrane protein NPC1 that allows transport of cholesterol to the ER facilitating homeostasis . Defects in this pathwat result in Niemann-Pick type C disease, a severe and fatal condition.
Superb
Hats off 🙌
G even I can follow this. Great presentation
outstanding
Loved it awsmmmmmm💯
thanks
Nice!
thank u so much bestie
Thanks
Perfect thank you Guys for being here
So helpful. Thanks!
thank you ❤
Yes
je suis en 2e année de médecine en France et je comprenais rien grâce a toi j'ai compris la base de mon cours, MERCII
Tysm
Thank full😇😊
The voice is so soothing!!
Awesome
I learned in less than 5 minutes about Lipoproteins instead of 5 hours of biochemistry
Owo very very nice lecture
Thanks 🙏🙏🙏🙏
You are missing the transition from VLDL to LDL ( IDL ). Still great job
Jose Cordova, also the difference between liver derived LDL vs LDL derived from VLDL degradation.
wow
ok now i know how VLDL gets to LDL
and nice and simple diagrame for action of those drugs