HDL ( Reverse cholesterol transport)

hi in this video we'll talk about hdl and reverse cholesterol transport mediated by hdl hdl stands for high density lipoprotein that means hdl has more of a protein part than the lipid part now let me introduce you about hdl so hdl has apple lipoprotein a1 apple lipoprotein c that are the major component of hdl and hdl can be secreted from both intestine and the liver 40 of the hdl is actually protein 30 percent is phospholipid and 25 percent is cholesterol now just to compare hdl with other lipoprotein components hdl is known as good cholesterol so in this video we'll try to understand why hdl is good what's the benefit of hdl let us compare all these lipoprotein molecules there is chylomicron vldl idl ldl and hdl you can see the hdl is smaller in size in other word they have very high density of protein and very less amount of fat part so the major apple lipoproteins that make hdl unique is apple lipoprotein a1 which is not present in many other apple other particles now coming to the composition hdl is majorly consists of protein whereas ldl and other particles are either more triglyceride or cholesterol rich and hdl can be secreted both from liver and intestine so we know that ldl which is also known as bad cholesterol deposits cholesterol excess cholesterol in the arteries and this increase the risk of coronary artery diseases and they are hence atherogenic now in case of hdl they kind of scavenge these excess cholesterol from these arterial space and they return it to liver so they are kind of anti-atrogenic and better for our health now hdl has several other properties which make it unique hdl is a resolver for apple lipoprotein and many of these apple ipod proteins are supplied to other lipoprotein particles now hdl can uptake unesterified cholesterol hdf also helps in estrofication of cholesterol hdl takes part in reverse cholesterol transport that means it takes takes away excess of cholesterol which is deposited in the artery space and return it to the liver for recycling now ldl we know already deposited excess of cholesterol in the artery walls and hdl moves in the circulation collect those excess of cholesterol and return it to the liver and this selective process is known as the reverse cholesterol transport where peripheral cholesterol is now returned to the liver for recycling purposes and the cholesterol is now converted to colic acid which would ultimately be utilized from bile acids right now from ex from extra hepatic tissue from external tissue space cholesterol is collected with the help of several transporters such as abca1 which is present in almost all peripheral tissues now this abca1 mediates cholesterol export and cholesterol is converted to cholesterol ester with the help of the enzyme lcat or lecithin cholesterol lacile transferase then this hdl particle can be actually returned to the liver and in the liver there is sr1b receptor which is a scavenger receptor that scavenge hdl particle and thereby uptakes all the cholesterol inside it and release the hdl particle for next round of scavenging that what happens in the liver so this is how hdl deposits excess cholesterol in the liver now here is the foam cell which is a rich source of cholesterol and this deposits actually uh cholesterol in the artery space now cholesterol is uptaken by the nascent hdl particle with the help of abca1 and abcg1 receptor so all of these cholesterol is actually uptaken by the nascent hdl but nasal hdl is eating more and more cholesterol so it would become fat it would become bigger and forming hdl3 particles eventually hdl tree particle would have more of such cholesterol and triglyceride and they would become hdl2 particle finally this hdl2 particle would be returned to the liver and would be recycled again back to the nascent collapse nissan hdl now hdl can interact with vldl particle or idl particle and hdl give them protein whereas vldl and ideal particle give them triglycerides ultimately after taking triglycerides from vldl and ideal these particle can eventually become ldl now ldl can deposit cholesterol in the tissues but the other fate of ldl that it can be up taken by the liver inside the liver there are liver hepatocyte cells which have ldl receptors these ldl receptors leads to receptor mediated endocytosis and uptake of cholesterol so in other way hdl kind of indirectly favors the cholesterol uptake so there are two pathways by hdl mediates these cholesterol uptake one via these ldl particles or otherwise directly binding to the scavenger receptor present in the liver hepatocytes so in this video we overall looked at that hdl works like a garbage picking truck so wherever there is a garbage it picks it up and put it in the dump yard here the dump beard is analogous to the liver whereas the garbage which is sitting around near the road is actually the cholesterol present in the arterial plux which is picked up by the hdl particle and these excess cholesterol is deposited into the liver and thereby efficient recycling is happening which prevents our body from the risk of atherogenesis i hope you enjoyed this video if you like this video give it a big thumbs up don't forget to like share and subscribe thank you

Channel: Animated biology With arpan

Views: 24,320

Rating: 4.8650088 out of 5

Keywords: animation, video, health literacy, cholesterol, lipoproteins, hyperlipidemia, lipids, fatty acids, plaque, atherosclerosis, coronary artery disease, nucleus medical media, low-density lipoprotein, high-density lipoprotein (chemical compound), high-density lipoprotein, hdl-c, high density lipoprotein, reverse cholesterol transport, cholesterol efflux, good cholesterol, cetp, apo-a1, apo-b, ldl-c, atherosclerosis (disease or medical condition), niacin (drug), hdl animation, 3d animation

Id: T-jkTGM1fWw

Length: 6min 39sec (399 seconds)

Published: Sun Jul 26 2020